Multifocal lens having a progressive optical power region and a discontinuity

ABSTRACT

Embodiments of the present invention relate to a multifocal lens having a diffractive optical power region and a progressive optical power region. Embodiments of the present invention provide for the proper alignment and positioning of each of these regions, the amount of optical power provided by each of the regions, the optical design of the progressive optical power region, and the size and shape of each of the regions. The combination of these design parameters allows for an optical design having less unwanted astigmatism and distortion as well as both a wider channel width and a shorter channel length compared to conventional PALs. Embodiments of the present invention may also provide a new, inventive far-intermediate distance zone and may further provide for increased vertical stability of vision within a zone of the lens.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.12/839,088 filed Jul. 19, 2010, now U.S. Pat. No. 8,092,016, which is acontinuation of U.S. application Ser. No. 12/059,908 filed Mar. 31,2008, now abandoned which is a continuation-in-part of U.S. Ser. No.11/964,030 filed on 25 Dec. 2007 now U.S. Pat. No. 7,883,206, andentitled “Multifocal Lens Having a Progressive Optical Power Region anda Discontinuity”, which is incorporated herein by reference in itsentirety.

This application claims priority from and incorporates by reference intheir entirety the following provisional applications:

-   -   U.S. Ser. No. 60/907,367 filed on 29 Mar. 2007 and entitled        “Composite Advanced Progressive Addition Lens having a        Discontinuity”;    -   U.S. Ser. No. 60/924,975 filed on 7 Jun. 2007 and entitled        “Refined Toric & Spherical Curvatures Associated with a Low Add        Power Contributing Progressive Lens Region”;    -   U.S. Ser. No. 60/935,226 filed on 1 Aug. 2007 and entitled        “Combined Optics for Correction of Near and Intermediate        Vision”;    -   U.S. Ser. No. 60/935,492 filed on 16 Aug. 2007 and entitled        “Diamond Turning of Tooling to Generate Enhanced Multi-Focal        Spectacle Lenses”;    -   U.S. Ser. No. 60/935,573 filed on 20 Aug. 2007 and entitled        “Advanced Lens with Continuous Optical Power”; and    -   U.S. Ser. No. 60/956,813 filed on 20 Aug. 2007 and entitled        “Advanced Multifocal Lens with Continuous Optical Power”; and    -   U.S. Ser. No. 60/970,024 filed on 5 Sep. 2007 and entitled        “Refined Enhanced Multi-Focal”.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to multifocal ophthalmic lenses, lensdesigns, lens systems, and eyewear products or devices utilized on, inor about the eye. More specifically, the present invention relates tomultifocal ophthalmic lenses, lens designs, lens systems, and eyewearproducts which, in most cases, reduce unwanted distortion, unwantedastigmatism, and vision compromises associated with Progressive AdditionLenses to a very acceptable range for a wearer.

2. Description of the Related Art

Presbyopia is the loss of accommodation of the crystalline lens of thehuman eye that often accompanies aging. This loss of accommodation firstresults in an inability to focus on near distance objects and laterresults in an inability to focus on intermediate distance objects. Thestandard tools for correcting presbyopia are multifocal ophthalmiclenses. A multifocal lens is a lens that has more than one focal length(i.e., optical power) for correcting focusing problems across a range ofdistances. Multifocal ophthalmic lenses work by means of a division ofthe lens's area into regions of different optical powers. Typically, arelatively large area located in the upper portion of the lens correctsfor far distance vision errors, if any. A smaller area located in thebottom portion of the lens provides additional optical power forcorrecting near distance vision errors caused by presbyopia. Amultifocal lens may also contain a region located near the middleportion of the lens, which provides additional optical power forcorrecting intermediate distance vision errors. Multifocal lenses may becomprised of continuous or discontinuous surfaces that create continuousor discontinuous optical power.

The transition between the regions of different optical power may beeither abrupt and discontinuous, as is the case with bifocal andtrifocal lenses, or smooth and continuous, as is the case withProgressive Addition Lenses. Progressive Addition Lenses are a type ofmultifocal lens which comprises a gradient of continuously increasingpositive dioptric optical power from the far distance zone of the lensto the near distance zone in the lower portion of the lens. Thisprogression of optical power generally starts at or near what is knownas the fitting cross or fitting point of the lens and continues untilthe full add power is realized in the near distance zone of the lens.Conventional and state-of-the-art Progressive Addition Lenses utilize asurface topography on one or both exterior surfaces of the lens shapedto create this progression of optical power. Progressive Addition Lensesare known within the optical industry when plural as PALs or whensingular as a PAL. PALs are advantageous over traditional bifocal andtrifocal lenses because they can provide a user with a lineless,cosmetically pleasing multifocal lens with continuous vision correctionand no perceived image break as the user's focus transitions fromobjects at a far distance to objects at a near distance or vice versa.

While PALs are now widely accepted and in vogue within the United Statesand throughout the world as a correction for presbyopia, they also haveserious vision compromises. These compromises include, but are notlimited to, unwanted astigmatism, distortion, and swim. These visioncompromises may affect a user's horizontal viewing width, which is thewidth of the visual field that can be seen clearly as a user looks fromside to side while focused at a given distance. Thus, PALs may have anarrow horizontal viewing width when focusing at an intermediatedistance, which can make viewing a large section of a computer screendifficult. Similarly, PALs may have a narrow horizontal viewing widthwhen focusing at a near distance, which can make viewing the completepage of a book or newspaper difficult. Far distance vision may besimilarly affected. PALs may also make it difficult for a wearer to playsports due to the distortion of the lenses. In addition to theselimitations, many wearers of PALs experience an unpleasant effect knownas visual motion (often referred to as “swim”) due to the distortionthat exists in each of the lenses. In fact, many people refuse to wearsuch lenses because of the discomfort from this effect.

When considering the near distance optical power needs of a presbyopicindividual, the amount of near distance optical power required isinversely proportional to the amount of accommodative amplitude (neardistance focusing ability) the individual has left in his or her eyes.Generally, as an individual ages the amount of accommodative amplitudedecreases. Accommodative amplitude may also decrease for various healthreasons. Therefore, as one ages and becomes more presbyopic, the opticalpower needed to correct one's ability to focus at a near distance and anintermediate distance becomes stronger in terms of the needed dioptricoptical power. The near and intermediate distance optical power isusually stated in terms of an “add power” or “additive optical power”.An add power is the amount of optical power over the far distance visioncorrection. Add power usually refers to the optical power added to thefar distance vision correction to achieve proper near distance visioncorrection. For example, if one has −1.00 D of optical power correctionfor far distance viewing and +2.00 D of near distance add power such anindividual has +1.00 D of optical power correction for near distanceviewing.

By comparing the different near distance add power needs of twoindividuals, it is possible to directly compare each individual's nearpoint focusing needs. By way of example only, an individual 45 years oldmay need +1.00 D of near distance add power to see clearly at a nearpoint distance, while an individual 80 years old may need +2.75 D to+3.50 D of near distance add power to see clearly at the same near pointdistance. Because the degree of vision compromises in PALs increaseswith dioptric add power, a more highly presbyopic individual will besubject to greater vision compromises. In the example above, theindividual who is 45 years of age will have a lower level of distortionand wider intermediate distance and near distance vision zonesassociated with his or her lenses than the individual who is 80 years ofage. As is readily apparent, this is the complete opposite of what isneeded given the quality of life issues associated with being elderly,such as frailty or loss of dexterity. Prescription multifocal lensesthat add compromises to vision function and inhibit safety are in sharpcontrast to lenses that make lives easier, safer, and less complex.

By way of example only, a conventional PAL with a +1.00 D near distanceadd power may have approximately 1.00 D or less of unwanted astigmatism.However, a conventional PAL with a +2.50 D near distance add power mayhave approximately 2.75 D or more of unwanted astigmatism while aconventional PAL with a +3.25 D near distance add power may haveapproximately 3.75 D or more of unwanted astigmatism. Thus, as a PAL'snear distance add power increases (for example, a +2.50 D PAL comparedto a +1.00 D PAL), the unwanted astigmatism found within the PALincreases at a greater than linear rate.

More recently, a double-sided PAL has been developed which has aprogressive addition surface topography placed on each external surfaceof the lens. The two progressive addition surfaces are aligned androtated relative to one another to not only give the appropriate totaladditive near distance add power required, but also to have the unwantedastigmatism created by the PAL on one surface of the lens counteractsome of the unwanted astigmatism created by the PAL on the other surfaceof the lens. Even though this design reduces the unwanted astigmatismand distortion for a given near distance add power as compared totraditional PALs, the level of unwanted astigmatism, distortion, andother vision compromises listed above still causes serious visionproblems for certain wearers.

Other multifocal lenses have been developed which provide for theplacement of continuous and/or discontinuous optical elements in opticalcommunication with one another. However, these lenses have not realizedan optimal placement and alignment of the continuous and/ordiscontinuous elements. These lenses have also failed to realize anoptimal optical power distribution in the optical elements placed inoptical communication. Therefore, these lenses typically have one ormore perceived image breaks, prismatic image jump, cosmetic issues,surface discontinuities, poor vision ergonomics, and/or an optical powergradient that is too steep. These issues typically translate into visualfatigue, eyestrain, and headaches for a wearer of these lenses. Theselenses have also failed to realize an upper far-intermediate distancezone, a far-intermediate zone having a plateau of optical power, and/oran intermediate zone having a plateau of optical power.

Therefore, there is a pressing need to provide a spectacle lens and/oreyewear system that satisfies the vanity needs of presbyopic individualsand at the same time corrects their presbyopia in a manner that reducesdistortion and blur, widens the horizontal viewing width, allows forimproved safety, and allows for improved visual ability when playingsports, working on a computer, and reading a book or newspaper.

SUMMARY OF THE INVENTION

In an embodiment of the present invention, an ophthalmic lens may have afar distance zone. The ophthalmic lens may include a diffractive opticalpower region for providing a first incremental add optical power. Theophthalmic lens may further include a discontinuity located between thefar distance zone and the diffractive optical power region. Theophthalmic lens may further include a progressive optical power regionfor providing a second incremental add power, wherein at least a portionof the diffractive optical power region and the progressive opticalpower region are in optical communication such that the firstincremental add power and the second incremental add power togetherprovide a near distance add power for a user.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will be understood and appreciated morefully from the following detailed description in conjunction with thefigures, which are not to scale, in which like reference numeralsindicate corresponding, analogous or similar elements, and in which:

FIGS. 1A-13B show different lenses either having a perceived image breakor not having a perceived image break according to embodiments of thepresent invention;

FIG. 14A shows a view of the front surface of a lens having two opticalpower regions and a blend zone according to an embodiment of the presentinvention;

FIG. 14B shows a view of the front surface of a lens having two opticalpower regions and a blend zone according to an embodiment of the presentinvention;

FIG. 14C shows a view of the back surface of the lens of FIG. 14A orFIG. 14B having a progressive optical power region below a fitting pointof the lens according to an embodiment of the present invention;

FIG. 14D shows a view of the back surface of the lens of FIG. 14A orFIG. 14B having a progressive optical power region at or near a fittingpoint of the lens according to an embodiment of the present invention;

FIG. 14E shows a cross-sectional view of the lens of FIGS. 14A and 14Ctaken through the center vertical line of the lens according to anembodiment of the present invention;

FIG. 14F shows the lens of FIGS. 14A and 14C from the front showing theplacement and optical alignment of the optical power regions on thefront and back surfaces of the lens according to an embodiment of thepresent invention;

FIG. 14G shows the lens of FIGS. 14B and 14C from the front showing theplacement and optical alignment of the optical power regions on thefront and back surfaces of the lens according to an embodiment of thepresent invention;

FIG. 15A shows a view of the front surface of a lens having two opticalpower regions and a blend zone according to an embodiment of the presentinvention;

FIG. 15B shows a view of the back surface of the lens of FIG. 15A havinga progressive optical power region below a fitting point of the lensaccording to an embodiment of the present invention;

FIG. 15C shows a lens having a surface which is the mathematicalcombination of the surface of FIG. 15A and the surface of FIG. 15Baccording to an embodiment of the present invention;

FIG. 15D shows a diagram pictorially explaining how the surfaces ofFIGS. 15A and 15B are combined to form the surface of FIG. 15C accordingto an embodiment of the present invention;

FIG. 16 shows an add power gradient as measured by a Rotlex Class Plus™trademarked by Rotlex for an Essilor Physio™ lens trademarked byEssilor, an Essilor Ellipse™ lens trademarked by Essilor, and a ShamirPiccolo™ lens trademarked by Shamir Optical each having a near distanceadd power of +1.25 D according to an embodiment of the presentinvention;

FIG. 17 shows measurements taken from the fitting point down the channelof the add power found in the three lenses of FIG. 16 as measured by aRotlex Class Plus™ according to an embodiment of the present invention;

FIG. 18 shows measurements taken from the fitting point down the channelof the add power found in embodiments of the present invention in whicha mostly spherical power region having an optical power of +1.00 D isplaced in optical communication with the lenses of FIG. 16;

FIG. 19 shows an add power gradient for both an embodiment of thepresent invention on the left and an Essilor Physio™ lens on the rightas measured by a Rotlex Class Plus™;

FIG. 20 shows measurements taken from the fitting point down the channelof the add power found in the two lenses of FIG. 19 as measured by aRotlex Class Plus™ according to an embodiment of the present invention;

FIG. 21 shows four regions of a lens: a far distance zone, an upperfar-intermediate distance zone, an intermediate distance zone, and anear distance zone according to an embodiment of the present invention;

FIGS. 22-23 show the optical power along the center vertical mid-line ofembodiments of the present invention including a progressive opticalpower region connecting the far distance zone to the near distance zone;

FIG. 24-26 shows the optical power along the center vertical mid-line ofembodiments of the present invention including a mostly spherical powerregion, a discontinuity, and a progressive optical power regionconnecting the far distance zone to the near distance zone;

FIGS. 27A-27C show embodiments of the present invention having a blendzone with a substantially constant width located at or below a fittingpoint of the lens;

FIGS. 28A-28C shows embodiments of the present invention having a blendzone including a portion with a width of substantially 0 mm (therebyproviding a transition in this portion similar to a lined bifocal)located at or below a fitting point of the lens; and

FIGS. 29A-29D show methods of manufacturing a composite lens accordingto embodiments of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Many ophthalmological, optometric, and optical terms are used in thisapplication. For the sake of clarity, their definitions are listedbelow:

Add Power: Add power represents the additional plus optical powerrequired for near distance vision and/or intermediate distance vision.It is most commonly prescribed for presbyopia when the normalaccommodative power of the eye is no longer sufficient to focus on neardistance or intermediate distance objects. It is called an “add” power,because it is in addition to the far distance optical power of a lens.For example, if an individual has a far distance viewing prescription of−3.00 D and a +2.00 D add power for near distance viewing then theactual optical power in the near distance portion of the multifocal lensis the sum of the two powers, or −1.00 D. Add power is sometimesreferred to as plus optical power or additive optical power. Add powermay also refer to the add power in the intermediate distance portion ofthe lens and is called the “intermediate distance add power”. Typically,the intermediate distance add power is approximately 50% of the neardistance add power. Thus, in the example above, the individual wouldhave +1.00 D add power for intermediate distance viewing and the actualtotal optical power in the intermediate distance portion of themultifocal lens would be −2.00 D.

Blend Zone: A zone which transitions the optical power difference acrossat least a portion of an optical power discontinuity of a lens, wherethe discontinuity is located between a first optical power and a secondoptical power. The difference between the first and second opticalpowers may be caused, for example, by different surface topographies orby different indices of refraction. The optical power transitionscontinuously from the first optical power to the second optical poweracross the blend zone. When diffractive optics are used, the blend zonecan include blending the optical efficiency of the peripheral region ofthe diffractive optics. A blend zone is utilized for cosmeticenhancement reasons. A blend zone is typically not considered a usableportion of the lens due to its poor optics. A blend zone is also knownas a transition zone.

Channel: The region of a lens defined by increasing plus optical power,centered by the umbilic of the lens, which extends from the far distancezone to the near distance zone and is free of unwanted astigmatismgreater than 1.00 D. For a Progressive Addition Lens this optical powerprogression starts approximately in an area of the lens known as thefitting point and ends in the near distance zone. However, inembodiments of the present invention which have a progressive opticalpower region, the channel may start between approximately 4 mm andapproximately 10 mm below the fitting point. The channel is sometimesreferred to as the corridor.

Channel Length: The channel length is the distance measured from thedefined start of the channel where the optical power first begins toincrease to the location in the channel where the add power is withinapproximately 85% of the specified near distance viewing power of thelens. For a PAL, the channel typically starts at or near the fittingpoint.

Channel Width: The narrowest portion of the channel bounded by anunwanted astigmatism that is above approximately 1.00 D. This definitionis useful when comparing lenses, due to the fact that a wider channelwidth generally correlates with less blur, less distortion, bettervisual performance, increased visual comfort, and easier adaptation tothe channel for the wearer.

Continuous Optical Power: Optical power that is either substantiallyconstant or that changes in a manner that does not create a perceivedimage break.

Continuous Surface: A refractive surface that does not cause a perceivedimage break. A continuous surface can be external or internal to thelens. If internal, it would have a different index of refraction thanthe material adjacent to it. An example of a continuous surface is thesurface of a substantially spherical lens or a Progressive AdditionLens.

Contour Maps: Plots that are generated from measuring and plotting theoptical power changes and/or the unwanted astigmatic optical power of alens. A contour plot can be generated with various sensitivities ofastigmatic optical power thus providing a visual picture of where, andto what extent a lens possesses unwanted astigmatism as an effect due toits optical design. Analysis of such maps can be used to quantify thechannel length, channel width, reading width and far distance width of alens. Contour maps may be referred to as unwanted astigmatic power maps,sphere power maps, mean power maps, add power maps, or power error maps.These maps can also be used to measure and portray optical power invarious parts of the lens.

Conventional Channel Length: Due to aesthetic concerns or trends ineyewear fashion, it may be desirable, due to frame styles, to have alens that is foreshortened vertically to fit the frame. In such a lens,to deliver sufficient near distance vision, the channel is naturallyalso shortened. Conventional channel length refers to the length of achannel in a non-foreshortened lens. These channel lengths are usually,but not always, approximately 15 mm or longer. Generally, a longerchannel length means a wider channel width and less unwanted astigmatismcompared to PALs with a shorter channel length.

Discontinuity: A discontinuity is an optical power change or a surfacechange that results in a perceived image break for a user. Adiscontinuity may be caused by a step up or a step down in optical powerbetween two regions of a lens. For example, a discontinuity of 0.10 Drefers to a step up or down of 0.10 D between two regions of a lens.

Discontinuous Optical Power: Optical power that changes in a manner thatcreates a perceived image break.

Discontinuous Surface: A surface that causes a perceived image break. Adiscontinuous surface can be external or internal to the lens. Ifinternal, it would have a different index of refraction than thematerial adjacent to it. By way of example only, a discontinuous surfaceis the surface of a lined bifocal lens where the surface changes fromthe far distance zone to the near distance zone of the lens.

Dynamic lens: A lens with an optical power that is alterable with theapplication of electrical energy, mechanical energy, or force. Theoptical power of a dynamic lens is alterable without additional grindingor polishing. Either the entire lens may have an alterable opticalpower, or only a portion, region, or zone of the lens may have analterable optical power. The optical power of such a lens is dynamic ortunable such that the optical power can be switched between two or moreoptical powers. One of the optical powers may be that of substantiallyno optical power. Examples of dynamic lenses include electro-activelenses, electrical meniscus lenses, a lens having one or moremechanically moving parts, or a lens made from a conformable membranesuch as a gas lens or a fluid lens. A dynamic lens may also be referredto as a dynamic optic or a dynamic optical element. A dynamic lens mayalso be referred to as a transmissive adaptive optic or lens.

Far-Intermediate Distance Zone: The portion or region of a lenscontaining an optical power which allows a user to see clearly at afar-intermediate distance. The far-intermediate distance zone may belocated between the far distance zone and the intermediate distance zoneof a lens, in which case it is referred to as the “upperfar-intermediate distance zone”. It may also be located below the neardistance zone of the lens, in which case it is referred to as the “lowerfar-intermediate distance zone”. The far-intermediate distance zone mayalso be referred to as a far-intermediate vision zone.

Far-Intermediate Distance: The distance to which one looks, by way ofexample only, when viewing to the far edge of one's desk. This distanceis usually, but not always, considered to be between approximately 29inches and approximately 5 feet from the eye and in some cases may bebetween approximately 29 inches and approximately 10 feet from the eye.The far-intermediate distance may also be referred to as afar-intermediate viewing distance or a far-intermediate distance point.

Far Distance Reference Point: A reference point located approximately 4mm to approximately 8 mm above the fitting cross where the far distanceprescription or far distance optical power of a PAL can be easilymeasured.

Far Distance Zone: The portion or region of a lens containing an opticalpower which allows a user to see clearly at a far distance. The fardistance zone may also be referred to as the far vision zone.

Far Distance Width: The narrowest horizontal width within the fardistance viewing portion of the lens, approximately 4 mm toapproximately 8 mm above the fitting point, which provides clear, mostlyblur-free correction with an optical power within 0.25 D of the wearer'sfar distance optical power correction.

Far Distance: The distance to which one looks, by way of example only,when viewing beyond the edge of one's desk, when driving a car, whenlooking at a distant mountain, or when watching a movie. This distanceis usually, but not always, considered to be greater than approximately5 feet from the eye and in some cases may be greater than approximately10 feet from the eye. “Far distance” is not to be confused with farinfinity which is approximately 20 feet or further from the eye. At farinfinity, the eye's accommodative system is fully relaxed. The opticalpower provided in one's optical prescription to correct forapproximately 5 feet (or 10 feet) from the eye or greater is typicallynot significantly different from the optical power needed to correct forapproximately 20 feet from the eye. Therefore, as used herein, fardistance refers to distances approximately 5 feet (or 10 feet) from theeye and greater. The far distance may also be referred to as far viewingdistance or a far distance point.

Fitting Cross/Fitting Point: A reference point on a lens that representsthe approximate location of a wearer's pupil when looking straight aheadthrough the lens once the lens is mounted in an eyeglass frame andpositioned on the wearer's face. The fitting cross/fitting point isusually, but not always, located approximately 2 mm to approximately 5mm vertically above the start of the channel. The fitting cross may havea very slight amount of plus optical power ranging from just over +0.00D to approximately +0.12 D. In some cases, this point or cross may beink-marked on the lens surface to provide an easily viewable referencepoint for measuring and/or double-checking the fitting of the lensrelative to the pupil of the wearer. The mark is easily removed upondispensing the lens to the wearer.

Hard or Soft Progressive Addition Region: A progressive addition zonewith a fast or slow rate of optical power change or astigmatic powerchange is referred to as a hard or soft progressive addition region,respectively. A lens that contains mostly fast rates of change may bereferred to as a “hard progressive addition lens”. A lens that containsmostly slow rates of change may be referred to as a “soft progressiveaddition lens”. PALs may contain both hard and soft zones depending onthe corridor length chosen, add power needed, and the designer'smathematical tools.

Hard Progressive Addition Lens: A Progressive Addition Lens with a lessgradual, steeper transition between the far distance correction and thenear distance correction. In a hard PAL, the unwanted distortion may bebelow the fitting point and not spread out into the periphery of the fardistance region of the lens. A hard PAL may, in some cases, also have ashorter channel length and a narrower channel width. A “modified hardProgressive Addition Lens” is a PAL which comprises a slightly modifiedhard PAL optical design having one or more characteristics of a soft PALsuch as: a more gradual optical power transition, a longer channel, awider channel, more unwanted astigmatism spread out into the peripheryof the lens, and less unwanted astigmatism below the fitting point.

Horizontal Stability of Optical Power: A region or zone of a lens thathas mostly constant optical power across the horizontal width of theregion or zone. Alternatively, the optical power change may be anaverage of approximately 0.05 D per millimeter or less across thehorizontal width of the region or zone. As another alternative, theoptical power change may be an average of approximately 0.10 D permillimeter or less across the horizontal width of the region or zone. Asa final alternative, the optical power change may be an average ofapproximately 0.20 D per millimeter or less across the horizontal widthof the region or zone. The region or zone may have a horizontal width ofapproximately 1 mm or greater. As an alternative, the region or zone mayhave a horizontal width of approximately 1 mm to approximately 3 mm orgreater. As a final alternative, the region or zone may have ahorizontal width of approximately 2 mm to approximately 6 mm or greater.The region or zone may be the far distance zone, the upperfar-intermediate distance zone, the intermediate distance zone, the neardistance zone, the lower far-intermediate distance zone, or any otherregion of the lens.

Horizontal Stability of Vision: A region or zone of a lens is said tohave horizontal stability of vision if the region or zone has mostlyconstant, clear vision as a user looks left and right across the regionor zone. The region or zone may have a horizontal width of approximately1 mm or greater. As an alternative, the region or zone may have ahorizontal width of approximately 1 mm to approximately 3 mm or greater.As a final alternative, the region or zone may have a horizontal widthof approximately 2 mm to approximately 6 mm or greater. The region orzone may be the far distance zone, the upper far-intermediate distancezone, the intermediate distance zone, the near distance zone, the lowerfar-intermediate distance zone, or any other region of the lens.

Image break: An image break is a perceived disruption in an image whenlooking through a lens. When an image break occurs, the image perceivedthrough the lens is no longer seamless. An image break can be aprismatic displacement of the image across the image break, amagnification change of the image across the image break, a suddenblurring of the image at or around the image break, or some combinationof the three. One method of determining whether a lens has an imagebreak is to place the lens a fixed distance over a set of verticallines, horizontal lines, or a grid. FIGS. 1A-10B show different lenseshaving −1.25 D far distance correction and +2.25 D add power held 6″from a laptop screen displaying either vertical lines or a gridphotographed 19.5″ from the laptop screen. FIGS. 1A and 1B show a lensaccording to an embodiment of the present invention. FIGS. 2A and 2Bshow a lens according to another embodiment of the present invention.FIGS. 3A and 3B show a lens according to another embodiment of thepresent invention. FIGS. 4A and 4B show a lens according to anotherembodiment of the present invention. FIGS. 5A and 5B show a flat toppoly lens. FIGS. 6A and 6B show an easy top lens with slab-off prism.FIGS. 7A and 7B show an easy top lens. FIGS. 8A and 8B show a blendedbifocal lens. FIGS. 9A and 9B show a flat top trifocal lens. FIGS. 10Aand 10B show an executive lens. FIGS. 11A and 11B show a Sola SmartSeg™lens trademarked by Sola Optical having −2.25 D far distance correctionand +2.00 D add power held 6″ from a laptop screen displaying eithervertical lines or a grid photographed 19.5″ from the laptop screen.FIGS. 12A-13B show different lenses having −1.25 D far distancecorrection and +2.25 D add power held 6″ from a laptop screen displayingeither vertical lines or a grid photographed 19.5″ from the laptopscreen. FIGS. 12A and 12B show a Varilux Physio 360™ lens trademarked byEssilor. FIGS. 13A and 13B show a Sola Compact Ultra™ lens trademarkedby Carl Zeiss Vision. The lenses shown in FIGS. 1A-11B are lenses whichproduce a perceived image break. The lenses shown in FIGS. 12A-13B arelenses which do not produce a perceived image break.

Incremental Add Power: An add power that is less than the total addpower required for a user to see clearly at a near distance. A regionhaving an incremental add power typically has a maximum add power thatis less than the total add power required for a user to see clearly at anear distance. Two or more regions, each having an incremental addpower, may be placed in optical communication with each other. Becausethe regions are in optical communication with each other, the individualincremental add powers may be additive to create a total combinedincremental add power that is equal to the add power required for a userto see clearly at a near distance. The incremental add power of a regionmay be generated refractively or diffractively using a refractive opticor a diffractive optic, respectively. In some cases, a region may haveless than the total add power required for a user to see clearly at anintermediate distance. In such a case, the region is said to have an“incremental intermediate distance add power”.

Intermediate Distance Zone: The portion or region of a lens containingan optical power which allows a user to see clearly at an intermediatedistance. The intermediate distance zone may also be referred to as theintermediate vision zone.

Intermediate Distance: The distance to which one looks, by way ofexample only, when reading a newspaper, when working on a computer, whenwashing dishes in a sink, or when ironing clothing. This distance isusually, but not always, considered to be between approximately 16inches and approximately 29 inches from the eye. The intermediatedistance may also be referred to as an intermediate viewing distance andan intermediate distance point. It should be pointed out that“intermediate distance” can also be referred to as “near-intermediatedistance” since “near distance” is between approximately 10 inches toapproximately 16 inches from the eye. Alternatively, only a portion ofthe “intermediate distance” which is closest to approximately 16 inchesmay be referred to as a “near-intermediate distance”. “Far-intermediatedistance” is not to be confused with “intermediate distance”.“Far-intermediate distance” is instead between approximately 29 inchesto approximately 5 feet (or 10 feet) from the eye.

Lens: Any device or portion of a device that causes light to converge ordiverge. A lens may be refractive or diffractive. A lens may be eitherconcave, convex, or plano on one or both surfaces. A lens may bespherical, cylindrical, prismatic, or a combination thereof. A lens maybe made of optical glass, plastic, thermoplastic resins, thermosetresins, a composite of glass and resin, or a composite of differentoptical grade resins or plastics. A lens may be referred to as anoptical element, optical preform, optical wafer, finished lens blank, oroptic. It should be pointed out that within the optical industry adevice can be referred to as a lens even if it has zero optical power(known as plano or no optical power). A lens is normally oriented as aperson would wear the lens, such that the far distance zone of the lensis at the top and the near distance portion is at the bottom. The terms“upper”, “lower”, “above”, “below”, “vertical”, “horizontal”, “up”,“down”, “left”, “right”, “top”, and “bottom” when used in reference to alens may be taken with respect to this orientation.

Lens Blank: A device made of optical material that may be shaped into alens. A lens blank may be “finished” meaning that the lens blank hasboth of its external surfaces shaped into refractive external surfaces.A finished lens blank has an optical power which may be any opticalpower including zero or plano optical power. A lens blank may be a“semi-finished” lens blank, meaning that the lens blank has been shapedto have only one finished refractive external surface. A lens blank maybe an “unfinished” lens blank, meaning that neither external surface ofthe lens blank has been shaped into a refractive surface. An unfinishedsurface of an unfinished or semi-finished lens blank may be finished bymeans of a fabrication process known as free-forming or by moretraditional surfacing and polishing. A finished lens blank has not hadits peripheral edge shaped, edged, or modified to fit into an eyeglassframe. For the purposes of this definition a finished lens blank is alens. However, once a lens blank is shaped, edged, or modified to fit aneyeglass frame it is no longer referred to as a lens blank.

Lined Multifocal Lens: A multifocal lens that has two or more adjacentregions of different optical power having a visible discontinuity thatcan be seen by someone looking at a wearer of the lens. Thediscontinuity causes a perceived image break between the two or moreregions. Examples of a lined multifocal lens are lined (non-blended)bifocals or trifocals.

Lineless Multifocal Lens: A multifocal lens that has two or moreadjacent regions of different optical power having either nodiscontinuity between the two or more regions such as in a progressiveaddition lens or an invisible discontinuity between the two or moreregions which can not be seen by someone looking at a wearer of thelens. The discontinuity causes a perceived image break between the twoor more regions. An example of a lineless multifocal lens having adiscontinuity is a blended bifocal. A PAL can also be referred to as alineless multifocal, but a PAL does not have a discontinuity.

Low Add Power PAL: A Progressive Addition Lens that has less than thenecessary near add power for the wearer to see clearly at a near viewingdistance (i.e., it has an incremental add power).

Low Add Power Progressive Optical Power Region: A progressive opticalpower region that has less than the necessary near add power for thewearer to see clearly at a near viewing distance (i.e., it has anincremental add power).

Multifocal Lens: A lens having more than one focal point or opticalpower. Such lenses may be static or dynamic. Examples of staticmultifocal lenses include a bifocal lens, a trifocal lens or aProgressive Addition Lens. Dynamic multifocal lenses include, by way ofexample only, electro-active lenses. Various optical powers may becreated in the electro-active lens depending on the types of electrodesused, voltages applied to the electrodes, and index of refractionaltered within a thin layer of liquid crystal. Dynamic multifocal lensesalso include, by way of example only, lenses comprising a conformableoptical member such as gas lenses and fluid lenses, mechanicallyadjustable lenses where two or more movable members adjust the opticalpower, or electrical meniscus lenses. Multifocal lenses may also be acombination of static and dynamic. For example, an electro-activeelement may be used in optical communication with a static sphericallens, a static single vision lens, a static multifocal lens such as, byway of example only, a Progressive Addition Lens, a flat top 28 bifocal,or a flat top 7×28 trifocal. In most, but not all, cases, multifocallenses are refractive lenses. In certain cases, a multifocal lens maycomprise diffractive optics and/or a combination of diffractive andrefractive optics.

Near Distance Zone: The portion or region of a lens containing anoptical power which allows a user to see clearly at a near distance. Thenear distance zone may also be referred to as the near vision zone.

Near Distance: The distance to which one looks, by way of example only,when reading a book, when threading a needle, or when readinginstructions on a pill bottle. This distance is usually, but not always,considered to be between approximately 10 inches and approximately 16inches from the eye. The near distance may also be referred to as a nearviewing distance or a near distance point.

Office Lens/Office PAL: A specially designed occupational ProgressiveAddition Lens that replaces the far distance vision zone with that of amostly intermediate distance vision zone and typically provides neardistance vision in a near distance zone and intermediate distance visionin an intermediate distance zone. The optical power degresses from thenear distance zone to the intermediate distance zone. The total opticalpower degression is less optical power change than the wearer's typicalnear distance add power. As a result, wider intermediate distance visionis provided by a wider channel width and also a wider reading width.This is accomplished by means of an optical design which typicallyallows greater values of unwanted astigmatism above the fitting cross.Because of these features, this type of PAL is well-suited for deskwork, but one cannot drive his or her car or use it for walking aroundthe office or home since the lens contains little if any far distanceviewing area.

Ophthalmic Lens: A lens suitable for vision correction which includes,by way of example only, a spectacle lens, a contact lens, anintra-ocular lens, a corneal in-lay, and a corneal on-lay.

Optical Communication: The condition whereby two or more optical powerregions are aligned in a manner such that light passes through thealigned regions and experiences a combined optical power equal to thesum of the optical power of each individual region at the points throughwhich the light passes. The regions may be embedded within a lens or onopposite surfaces of the same lens or different lenses.

Optical Power Region: A region of a lens having an optical power.

Plateau of Optical Power: A region or zone of a lens that has mostlyconstant optical power across the horizontal width and/or verticallength of the region or zone. Alternatively, the optical power changemay be an average of approximately 0.05 D per millimeter or less acrossthe horizontal width and/or vertical length of the region or zone. Asanother alternative, the optical power change may be an average ofapproximately 0.10 D per millimeter or less across the horizontal widthand/or vertical length of the region or zone. As a final alternative,the optical power change may be an average of approximately 0.20 D permillimeter or less across the horizontal width and/or vertical length ofthe region or zone. The region or zone may have a horizontal widthand/or vertical length of approximately 1 mm or greater. As analternative, the region or zone may have a horizontal width and/orvertical length of approximately 1 mm to approximately 3 mm or greater.As a final alternative, the region or zone may have a horizontal widthand/or vertical length of approximately 2 mm to approximately 6 mm orgreater. A plateau of optical power allows for vertical stability ofoptical power and/or horizontal stability of optical power within theregion. A plateau of optical power would be recognized visually by awearer of a lens by moving his or her chin up and down or by lookingleft and right. If a region has a plateau of optical power the wearerwill notice that an object at a given distance stays mostly in focusthroughout the region. The region or zone may be the far distance zone,the upper far-intermediate distance zone, the intermediate distancezone, the near distance zone, the lower far-intermediate distance zone,or any other region of the lens.

Progressive Addition Region: A continuous region of a PAL thatcontributes a continuous, increasing optical power between the fardistance zone of the PAL and the near distance zone of the PAL. The addpower in the far distance zone at the start of the region isapproximately +0.10 D or less. In some cases, the region may contributea decreasing optical power after the full add power is reached in thenear distance zone of the lens.

Progressive Addition Surface: A continuous surface of a PAL thatcontributes a continuous, increasing optical power between the fardistance zone of the PAL and the near distance zone of the PAL. The addpower in the far distance zone at the start of the surface isapproximately +0.10 D or less. In some cases, the surface may contributea decreasing optical power after the full add power is reached in thenear distance zone of the lens.

Progressive Optical Power Region: A region of a lens having a firstoptical power, typically in an upper portion of the region and a secondoptical power, typically in a lower portion of the region wherein acontinuous change in optical power exists therebetween. A progressiveoptical power region may be on a surface of a lens or embedded within alens. A progressive optical power region may comprise one or moresurface topographies known as a “progressive optical power surface”. Aprogressive optical power surface may be on either surface of a lens orburied within the lens. A progressive optical power region is said to“begin” or “start” when the optical power is increased above theadjacent vision zone's optical power. Typically, this increase is a plusoptical power of +0.12 D or greater. The increased plus optical power atthe start of the progressive optical power region may be caused by amostly continuous increase in positive optical power. Alternatively, theadd power at the start of the progressive optical power region may becaused by a step in optical power which is either part of theprogressive optical power region or part of a different optical powerregion. The step in optical power may be caused by a discontinuity. Theoptical power of the progressive optical power region may decrease afterreaching its maximum add power. A progressive optical power region maybegin at or near the fitting point as in a conventional ProgressiveAddition Lens or may begin below the fitting point as in embodiments ofthe present invention.

Reading Width: The narrowest horizontal width within the near distanceviewing portion of the lens which provides clear, mostly distortion freecorrection with an optical power within 0.25 D of the wearer's neardistance viewing optical power correction.

Short Channel Length: Due to aesthetic concerns or trends in eyewearfashion, it may be desirable to have a lens that is foreshortenedvertically for fitting into a frame style which has a narrow, verticalheight. In such a lens the channel is naturally also shorter. Shortchannel length refers to the length of a channel in a foreshortenedlens. These channel lengths are usually, but not always betweenapproximately 9 mm and approximately 13 mm. Generally, a shorter channellength means a narrower channel width and more unwanted astigmatism.Shorter channel designs are sometimes referred to as having certaincharacteristics associated with “hard” Progressive Addition Lensdesigns, since the transition between far distance correction and neardistance correction is harder due to the steeper increase in opticalpower caused by the shorter vertical channel length.

Soft Progressive Addition Lens: A Progressive Addition Lens with a moregradual transition between the far distance correction and the neardistance correction. This more gradual transition causes an increasedamount of unwanted astigmatism. In a soft PAL the increased amount ofunwanted astigmatism may intrude above an imaginary horizontal linelocated through the fitting point that extends across the lens. A softPAL may also have a longer channel length and a wider channel width. A“modified soft Progressive Addition Lens” is a soft PAL which has amodified optical design having one or more of characteristics of a hardPAL such as: a steeper optical power transition, a shorter channel, anarrower channel, more unwanted astigmatism pushed into the viewingportion of the lens, and more unwanted astigmatism below the fittingpoint.

Static Lens: A lens having an optical power which is not alterable withthe application of electrical energy, mechanical energy, or force.Examples of static lenses include spherical lenses, cylindrical lenses,Progressive Addition Lenses, bifocals, and trifocals. A static lens mayalso be referred to as a fixed lens.

Step in Optical Power: An optical power difference between two opticalzones or regions that may result in an optical power discontinuity. Theoptical power difference may be a step up in optical power in whichoptical power increases between an upper portion and a lower portion ofa lens. The optical power difference may be a step down in optical powerin which optical power decreases between an upper portion and a lowerportion of a lens. For example, if an upper portion of a lens has anoptical power of +1.00 D, a “step up” in optical power of +0.50 D willresult in a lower portion of the lens immediately after the step up inoptical power (or discontinuity) having an optical power of +1.50 D. Theoptical power in the lower region is said to be “created” by the step inoptical power.

Unwanted Astigmatism: Unwanted astigmatism found within a lens that isnot part of the patient's prescribed vision correction, but rather is abyproduct of the optical design of the lens due to the smooth gradientof optical power that joins two optical power zones. Although, a lensmay have varying unwanted astigmatism across different areas of the lensof various dioptric powers, the term “unwanted astigmatism” generallyrefers to the maximum unwanted astigmatism that is found in the lens.Unwanted astigmatism may also be further characterized as the unwantedastigmatism located within a specific portion of a lens as opposed tothe lens as a whole. In such a case qualifying language is used toindicate that only the unwanted astigmatism within the specific portionof the lens is being considered. The wearer of the lens will perceiveunwanted astigmatism as blur and/or distortion caused by the lens. It iswell known and accepted within the optical industry that as long as theunwanted astigmatism and distortion of a lens is approximately 1.00 D orless, the user of the lens, in most cases, will barely notice it.

Vertical Stability of Optical Power: A region or zone of a lens that hasmostly constant optical power across the vertical length of the regionor zone. Alternatively, the optical power change may be an average ofapproximately 0.05 D per millimeter or less across the vertical lengthof the region or zone. As another alternative, the optical power changemay be an average of approximately 0.10 D per millimeter or less acrossthe vertical length of the region or zone. As a final alternative, theoptical power change may be an average of approximately 0.20 D permillimeter or less across the vertical length of the region or zone. Theregion or zone may have a vertical length of approximately 1 mm orgreater. As an alternative, the region or zone may have a verticallength of approximately 1 mm to approximately 3 mm or greater. As afinal alternative, the region or zone may have a vertical length ofapproximately 2 mm to approximately 6 mm or greater. The region or zonemay be the far distance zone, the upper far-intermediate distance zone,the intermediate distance zone, the near distance zone, the lowerfar-intermediate distance zone, or any other region of the lens.

Vertical Stability of Vision: A region or zone of a lens is said to havevertical stability of vision if the region or zone has mostly constantclear vision as a user looks up and down across the region or zone.However, it should be pointed out that while a PAL has clear vision fromthe far distance zone to the near distance zone, the optical powerbetween these zones is blended. Therefore, a PAL has blended stabilityof vision between the far distance and near distance zones. Thus, a PALhas a very limited vertical stability of optical power between the fardistance zone and the near distance zone. The region or zone may have avertical length of approximately 1 mm or greater. As an alternative, theregion or zone may have a vertical length of approximately 1 mm toapproximately 3 mm or greater. As a final alternative, the region orzone may have a vertical length of approximately 2 mm to approximately 6mm or greater. The region or zone may be the far distance zone, theupper far-intermediate distance zone, the intermediate distance zone,the near distance zone, the lower far-intermediate distance zone, or anyother region of the lens.

Embodiments of the present invention relate to an optical design, lens,and eyewear system that may solve many, if not most, of the problemsassociated with PALs. In addition, the embodiments may significantlyremove most of the vision compromises associated with PALs. Theembodiments may provide a means of achieving the proper far distance,intermediate distance, and near distance optical powers for the wearerwhile providing mostly continuous focusing ability for variousdistances. The embodiments may also provide a means of achieving theproper upper far-intermediate distance and/or lower far-intermediatedistance optical powers for the wearer while providing mostly continuousfocusing ability. The embodiments may have far less unwanted astigmatismthan a PAL. The embodiments may allow for a full range of presbyopiccorrection with add powers from +1.00 D to +3.50 D in either +0.12 Dsteps or +0.25 D steps. For add power prescriptions below +3.00 D, theembodiments typically keep the unwanted astigmatism to a maximum ofapproximately 1.00 D or less. For certain high add power prescriptionssuch as +3.00 D, +3.25 D, and +3.50 D, the embodiments typically keepthe unwanted astigmatism to a maximum of approximately 1.50 D.

Embodiments of the present invention may allow for optically combiningtwo discrete optical elements into one multifocal lens. The firstoptical element may have a mostly spherical power region thatcontributes a mostly spherical optical power. The mostly sphericaloptical power may be generated refractively or diffractively by arefractive optic or a diffractive optic, respectively. The secondoptical element may have a progressive optical power region thatcontributes a progressive optical power. The second optical elementcontributing progressive optical power may not provide enough add powerfor the user to see clearly at a near distance (i.e., the second opticalelement has an incremental add power). The first optical element maycontribute a mostly spherical optical power that provides an opticalpower in addition to that provided by the second optical element toallow the user to see clearly at a near distance (i.e., the firstoptical element has an incremental add power that when combined with thesecond optical element's incremental add power totals the user's neardistance add power). Because a portion of the total add power isprovided by the first optical element contributing mostly sphericaloptical power, the multifocal lens may have less unwanted astigmatismthan a PAL having the same total add power.

In an embodiment of the present invention, the first optical element maybe a buried diffractive optic having a different index of refractionthan the surrounding material of the lens. In another embodiment, thefirst optical element may be a buried refractive optic having adifferent index of refraction than the surrounding material of the lens.In another embodiment, the first optical element may be a buriedelectro-active element. In another embodiment, the first optical elementmay be on one or both surfaces of the lens and may be provided, forexample, by grinding, molding, surface casting, stamping, or freeforming an outer surface of the lens.

In an embodiment of the present invention, the second optical elementmay be on one or both surfaces of the lens and may be provided, forexample, by grinding, molding, surface casting, stamping, or freeforming an outer surface of the lens. In another embodiment, the secondoptical element may be buried within the lens and have a gradient ofindices of refraction different than the surrounding material of thelens. Typically, but not always, if one of the optical elements isburied within the lens, the other optical element is located on one orboth outer surfaces of the lens.

In an embodiment of the present invention, the first optical elementcontributing mostly spherical optical power is in optical communicationwith at least a portion of the second optical element contributingprogressive optical power. In another embodiment, the first opticalelement contributing mostly spherical optical power and the secondoptical element contributing progressive optical power aremathematically combined into a single optical element which may be on anouter refractive surface of the lens or buried within the lens.

Embodiments of the present invention provide for the proper alignmentand positioning of the first optical element contributing mostlyspherical optical power and the second optical element contributingprogressive optical power. Embodiments of the present invention alsoprovide for the amount of optical power provided by the mostly sphericalpower region, the amount of optical power provided by the progressiveoptical power region, and the optical design of the progressive opticalpower region. Embodiments of the present invention also provide for thesize and shape of the mostly spherical power region and the size andshape of the progressive optical power region. The combination of thesedesign parameters allows for a far superior optical design which hasless unwanted astigmatism and distortion as well as both a wider channelwidth and a shorter channel length compared to state of the art PALscommercially available today.

It should be pointed out that the figures, and any features shown in thefigures, are not drawn to scale. FIG. 14A shows a view of the frontsurface of a lens according to an embodiment of the present invention.FIG. 14B shows a view of the front surface of a different embodiment ofthe present invention. FIGS. 14A-14B show that the front convex surfaceof the lens has two optical power regions. The first optical powerregion is a far distance zone 1410 in the upper portion of the lens. Thesecond optical power region is a mostly spherical power region 1420 inthe lower portion of the lens that contributes an additive opticalpower. The additive optical power may be an incremental add power. InFIG. 14A, the mostly spherical power region is in the shape of an archedsection of the lens. The arched section may be thought of as a circularregion having a diameter much larger than the diameter of the lens.Because the circular region is too large for the lens, only the top archof its perimeter fits within the lens. In FIG. 14B, the mostly sphericalpower region is a circular shape. The mostly spherical power region islocated below a fitting point 1430. Alternatively, the mostly sphericalpower region may be located at or above the fitting point. Adiscontinuity in optical power exists between the far distance zone andthe mostly spherical power region. At least a portion of thediscontinuity may be blended by a blend zone 1440 located between thetwo optical power regions. The blend zone may be approximately 2.0 mmwide or less or approximately 0.5 mm wide or less. FIG. 14C shows a viewof the back surface of the lens of either FIG. 14A or FIG. 14B accordingto an embodiment of the present invention. FIG. 14C shows that the backconcave surface of the lens has a progressive optical power region 1450that contributes an additive optical power. The additive optical powermay be an incremental add power. It should be pointed out that when theprogressive optical power region is found on the back concave surface ofthe lens in most, but not in all, cases the back concave surface alsocomprises toric curves to correct for the patient's astigmaticrefractive error. The progressive optical power region starts below thefitting point of the lens. Alternatively, FIG. 14D shows a view of theback surface of the lens of either FIG. 14A or FIG. 14B according to anembodiment of the present invention in which the progressive opticalpower region starts at or near the fitting point of the lens. When theprogressive optical power region starts at the upper edge of the mostlyspherical power region, as in FIG. 14D, a step in optical power 1470 isprovided that is additive to the optical power provided at the start ofthe progressive optical power. When the progressive optical power regionbegins above the mostly spherical power region (not shown), the upperedge of the mostly spherical power region causes a discontinuity acrossthe channel of the progressive optical power region.

FIG. 14E shows a cross-sectional view of the lens of FIGS. 14A and 14Ctaken through the center vertical line of the lens according to anembodiment of the present invention. As can be seen in FIG. 14E, a fardistance optical power 1415 is provided in the far distance zone. Themostly spherical power region and the progressive optical power regionare aligned to be in optical communication with each other such that theoptical power contributed by each region combines in the near distancezone 1460 to provide a total near distance add power 1465 for the user.The progressive optical power region begins below the fitting point andends at or above the bottom of the lens. FIG. 14F shows the inventivelens from the front showing the placement and optical alignment of theoptical power regions of FIGS. 14A and 14C on the front and backsurfaces of the lens according to an embodiment of the presentinvention. FIG. 14G shows the inventive lens from the front showing theplacement and optical alignment of the optical power regions of FIGS.14B and 14C on the front and back surfaces of the lens according to anembodiment of the present invention. As can be seen in both FIGS. 14Fand 14G, the progressive optical power region starts at a portion of themostly spherical power region and is spaced apart and below thediscontinuity.

As mentioned above, in some embodiments of the present invention themostly spherical power region, blend zone, and progressive optical powerregion may be mathematically combined and located on a single surface ofthe lens. In an example of such an embodiment, a wearer of the lensrequires no correction for far distance and +2.25 D for near distancecorrection. FIG. 15A illustrates a mostly spherical power region 1510located in the bottom portion of a surface of a lens according to anembodiment of the present invention. The mostly spherical power regionmay generate optical power refractively. The lens has a blend zone 1520which transitions between the optical power in the far distance zone andthe optical power of the mostly spherical power region. By way ofexample only, in the lens of FIG. 15A, the mostly spherical power regionhas an optical power of +1.25 D and the far distance zone has a planooptical power. Thus, the mostly spherical power region may have anincremental add power. FIG. 15B illustrates a progressive optical powerregion 1530 located on a surface of a lens according to an embodiment ofthe present invention. As has been pointed out this could be on thefront convex surface, the back concave surface, or on both the frontconvex surface and the back concave surface. By way of example only, inthe lens of FIG. 15B, the progressive optical power region has an addpower of +1.00 D. Thus, the progressive optical power region may have anincremental add power. FIG. 15C illustrates a single surface of a lenswhich is a combination of the surface of the lens shown in FIG. 15A andthe surface of the lens shown in FIG. 15B according to an embodiment ofthe present invention. By way of example only, in the lens of FIG. 15C,the near distance zone optical power is +2.25 D which is a combinationof the +1.25 D of optical power contributed by the mostly sphericalpower region and the +1.00 D of optical power contributed by theprogressive optical power region. It should be noted that in FIG. 15Cthe progressive optical power region is optically aligned to start at aportion of the mostly spherical power region and is spaced apart andbelow the blend zone.

In some embodiments of the present invention the two surfaces may becombined by adding the geometries of the two surfaces togethermathematically thereby creating a new single surface. This new singlesurface may then be fabricated from a mold that may be produced byfree-forming or by diamond-turning. The mold can be used to producesemi-finished lens blanks that can be surfaced by any opticallaboratory.

By describing each of the two surfaces in terms of a geometric functionin Cartesian coordinates, the surface in FIG. 15A can be mathematicallycombined with the surface described in FIG. 15B to create the newsurface shown in FIG. 15C, which is a combination of the two surfaces.

The surface that defines or produces the mostly spherical power regionand blend zone may be divided into discrete equally sized sections. Eachsection may be described as a localized height or a localized curverelative to a fixed surface or fixed curvature, respectively. Such asurface can be described with the following equation:

${Z_{1}\left( {x,y} \right)} = {\sum\limits_{i = 0}^{n_{1}}{\sum\limits_{j = 0}^{n_{2}}{S\left( {x_{i},y_{j}} \right)}}}$

Similarly the surface that defines or produces the progressive opticalpower region may be divided into discrete equally sized sections thatare the same size as the above mentioned sections. Each section may bedescribed as a localized height or a localized curve relative to a fixedsurface or fixed curvature, respectively. Such a surface can bedescribed with the following equation:

${Z_{2}\left( {x,y} \right)} = {\sum\limits_{i = 0}^{n_{1}}{\sum\limits_{j = 0}^{n_{2}}{P\left( {x_{i},y_{j}} \right)}}}$

If the sections of the two surfaces are the same size, combiningsections from each surface is straightforward. The combined surface maythen be described by the simple superposition of the two surfaces or:Z ₃(x,y)=Z ₁(x,y)+Z ₂(x,y)

This process is illustrated in FIG. 15D according to an embodiment ofthe present invention.

The size of the sections should be as small as possible to achieve anaccurate representation of each surface. Further optimization of theprogressive optical power region may be done after the two surfaces arecombined, or the progressive optical power region can be pre-optimizedfor better combination with the mostly spherical power region and blendzone. If desired, the blend zone may not be combined and only the mostlyspherical power region and progressive optical power region arecombined.

The two surfaces may also be combined by the methods described is U.S.Pat. No. 6,883,916 to Menezes and U.S. Pat. No. 6,955,433 to Wooley, etal., both of which are hereby incorporated by reference in theirentirety.

The inventors have discovered the importance of a range of distancesthat has heretofore never been corrected in the same manner in theophthalmic arts. The range of distances lies between approximately 29inches and approximately 5 feet and has been found to be particularlyimportant for tasks such as focusing to the far edge of one's desk. Inthe prior art, this range of distances has been largely overlooked andhas been lumped together in prior art definitions with the category ofeither far distance or intermediate distance. Therefore, this range ofdistances has been corrected as part of one of these categories. Theinventors refer to this range of distances as a “far-intermediatedistance”. A new vision zone termed a “far-intermediate distance zone”has been invented to provide for proper focusing ability for thisinventive far-intermediate distance. Embodiments of the presentinvention may include this far-intermediate distance zone and mayoptimize the optical power in this zone to provide proper focusingability for a far-intermediate distance. Embodiments of the presentinvention may include this far-intermediate distance zone and mayoptimize the location of this zone in the lens to provide for properergonomic use of the lens. When this zone is located between the fardistance zone and the intermediate distance zone it is termed an “upperfar-intermediate distance zone”. When this zone is located below thenear distance zone it is termed a “lower far-intermediate distancezone”.

Typically, prior art multifocal lenses do not provide for properfocusing ability at a far-intermediate distance or provide for onlylimited focusing ability at a far-intermediate distance. For example,the far distance region or zone of bifocals is prescribed for anindividual wearer to allow for focusing ability at a far viewingdistance such as optical infinity which is approximately 20 feet orgreater. However, it should be noted that in most cases the same fardistance optical power will suffice for the wearer when viewingdistances of approximately 5 feet or greater. The near distance regionor zone of bifocals is prescribed to allow for focusing ability at anear viewing distance of approximately 10 inches to approximately 16inches. Trifocals allow for proper focusing ability at a far viewingdistance, a near viewing distance, and at an intermediate viewingdistance (from approximately 16 inches to approximately 29 inches). PALsprovide clear continuous vision between a far viewing distance and anear viewing distance. However, because the optical power in a PALcontinuously transitions from the far distance zone to the near distancezone, the vertical stability in this transition zone of the PAL is verylimited.

Unlike a PAL, embodiments of the present invention may provide forvertical stability in a particular zone or zones of the lens. Verticalstability in a zone may be provided by a step in optical power that maycause a discontinuity. In addition, embodiments of the present inventionmay provide for a location of the step or steps that is leastdistracting to a wearer's vision. Also, embodiments of the presentinvention may provide for forming the step or steps so they are mostlyinvisible when one looks at the face of a wearer of the lens.Embodiments of the present invention may also provide for forming thestep or steps so the wearer's eyes can comfortably translate over thestep or steps when looking from zone to zone such as, for example, whenlooking from the far distance zone to the near distance zone. Finally,in certain embodiments of the present invention the lens may provide forcontinuous uninterrupted focusing ability between approximately 4 to 5feet and approximately 10 inches to 12 inches from the eye of the wearerwith only a single discontinuity which is comfortably transitioned overwhen the wearer focuses between a far distance object and an object ator less than 4 to 5 feet from the wearer's eye. In still otherembodiments of the present invention the step in optical power may occurbetween the far distance zone and the intermediate distance zone wherebythe lens allows for continuous uninterrupted focusing ability betweenapproximately 29 inches and approximately 10 inches to 12 inches fromthe eye of the wearer with only a single discontinuity which iscomfortably transitioned over when the wearer focuses between a fardistance object and an object at or less than approximately 29 inchesfrom the wearer's eye.

In embodiments of the present invention it may be necessary to align themostly spherical power region and the progressive optical power regionto ensure that the correct total optical power is provided in thefar-intermediate zone and in the intermediate distance zone. Thefar-intermediate distance zone typically has an add power betweenapproximately 20% and approximately 44% of the near distance add power.The intermediate distance zone typically has an add power betweenapproximately 45% and approximately 55% of the near distance add power.It may also be necessary to align and position these regions to create ausable and ergonomically feasible lens for when the wearer's line ofsight transitions between the various zones (far distance zone,far-intermediate distance zone, intermediate distance zone, and neardistance zone). Lastly, it may also be necessary to design the gradientof optical power that exists between the far distance vision correctionand the near distance vision correction to ensure an optimalintermediate distance correction and/or far-intermediate distancecorrection.

In an embodiment of the present invention, the mostly spherical powerregion may be located between approximately 0 mm and approximately 7 mmbelow the fitting point. In another embodiment of the present invention,the mostly spherical power region may be located between approximately 2mm and approximately 5 mm below the fitting point. In an embodiment ofthe present invention, the progressive optical power region may start ata portion of the mostly spherical power region approximately 2 mm toapproximately 10 mm below the top edge of the mostly spherical powerregion. In another embodiment of the present invention, the progressiveoptical power region may start at a portion of the mostly sphericalpower region approximately 4 mm to approximately 8 mm below the top edgeof the mostly spherical power region. In an embodiment of the presentinvention, the far-intermediate distance power may start betweenapproximately 3 mm and approximately 4 mm below the fitting point andextend for approximately 4 mm down the channel. In an embodiment of thepresent invention, the intermediate distance power may start after thefar-intermediate distance zone and extend for approximately 3 mm toapproximately 4 mm down the channel. The aforementioned measurements areexemplary only, and are not intended to limit the present invention.

If the mostly spherical power region and progressive optical powerregion are not aligned and positioned properly, the user of the lenswill not have proper vision correction in usable portions of the lens.For example, if the mostly spherical power region is located much abovethe fitting point, the wearer may have too much optical power for fardistance viewing when looking straight ahead. As another example, if thelow add power progressive optical power region is located too high inthe lens, the combined optical power in the intermediate distance zoneprovided by the mostly spherical power region and the progressiveoptical power region may be too high for the wearer.

FIG. 16 and FIG. 17 show three conventional PAL designs (the EssilorPhysio™ lens trademarked by Essilor, the Essilor Ellipse™ lenstrademarked by Essilor, and the Shamir Piccolo™ lens trademarked byShamir Optical) having a near distance add power of +1.25 D according toembodiments of the present invention. FIG. 16 shows an add powergradient for the three lenses as measured by a Rotlex Class Plus™trademarked by Rotlex. FIG. 17 shows measurements taken every 3 mm fromthe fitting point down the channel of the add power in the three lensesas measured by a Rotlex Class Plus™.

FIG. 18 shows measurements taken every 3 mm from the fitting point downthe channel of the add power in three embodiments of the presentinvention. In these embodiments, the three lenses of FIG. 16 and FIG. 17are placed in optical communication with a mostly spherical power regionhaving an optical power of +1.00 D. In these embodiments, theprogressive optical power region starts at the fitting point and the topedge of the mostly spherical power region is placed just below thefitting point. As can be seen from FIG. 18, the add power of the lensesat 9 mm below the fitting point is too strong. The region of the lens 9mm below the fitting point would typically be part of the intermediatedistance zone. For a +2.25 D near distance add power the intermediatedistance add power should be +1.12 D. However, the Essilor Physio™embodiment has +1.63 D add power at 9 mm from the fitting point, theEssilor Ellipse™ embodiment has +1.82 D add power at 9 mm from thefitting point, and the Shamir Piccolo™ embodiment has +1.68 D add powerat 9 mm from the fitting point. Because there is too much add power inthe intermediate distance zone, a user of the lens may feel as if his orher eyes are pulling or crossing. This may cause headaches and the userwill have to hold objects closer to his or her eyes to focus properlythrough this zone. Thus, if the optical power, placement, and alignmentof the mostly spherical power region and progressive optical powerregion are not optimized, the resulting lens will have one or more ofthe following: poor vision ergonomics, poor vision comfort, and poorvision clarity.

As another example, FIG. 19 shows an add power gradient for both anembodiment of the present invention on the left and an Essilor Physio™lens on the right as measured by a Rotlex Class Plus™. Both theembodiment and the Physio™ lens have an add power of +2.25 D. Theembodiment has a mostly spherical power region having an optical powerof +1.25 D and a progressive optical power region having an add power of+1.00 D. The top of the progressive optical power region starts justbelow the fitting point and the top of the mostly spherical power regionis located 4 mm below the fitting point. Thus, there is a region of thelens where only the progressive optical power region contributesincreasing optical power before the mostly spherical power region beginsto add optical power to the lens. FIG. 20 shows measurements taken every3 mm from the fitting point down the channel of the add power in the twolenses of FIG. 19 as measured by a Rotlex Class Plus™. This embodimentof the present invention has an add power of +1.60 D at 9 mm from thefitting point compared to that of the Essilor Physio™ which has an addpower of +1.10 D at 9 mm from the fitting point. As before, if theoptical power, placement, and alignment of the mostly spherical powerregion and progressive optical power region are not optimized, theresulting lens will have poor vision ergonomics, poor vision comfort,and poor vision clarity. This is true even when the correct full addpower is provided by the lens as it is at 15 mm below the fitting pointin FIGS. 18 and 20.

Therefore, even though these embodiments of the present invention havenumerous superior attributes (such as less unwanted astigmatism)compared to state-of-the-art PALs, it should be obvious that such lenseswould be rejected by a user. The embodiments of the present inventionhave too much add power in the intermediate distance zone and theoptical power gradient from the fitting point to the bottom of the lensis too steep.

By comparing the add power measurements shown in FIG. 18 and FIG. 20 forthe Essilor Physio™ lens, it should be apparent that one cannot add a+1.00 D spherical power region to the Essilor Physio™ lens of FIG. 17and thereby approximate the Essilor Physio™ lens of FIG. 20. It shouldtherefore be apparent that the mostly spherical power region and/or theprogressive optical power region must be specifically designed to takeinto account the gradient of optical power between the far distance zoneand near distance zone to provide for a proper intermediate distancecorrection and/or far-intermediate distance correction.

FIG. 21 shows four regions of a lens: a far distance zone 2110, an upperfar-intermediate distance zone 2120, an intermediate distance zone 2130,and a near distance zone 2140 according to embodiments of the presentinvention. These regions are not shown to scale. The upperfar-intermediate distance zone may have a height from point H to point Iand a width from point A to point B. The intermediate distance zone mayhave a height from point I to point J and a width from point C to pointD. The near distance zone may have a height from point J to point G anda width from point E to point F. In certain embodiments of the presentinvention the inventive lens may provide proper correction for a wearerfor the far distance zone and the near distance zone and provide anoptimized gradient of optical power allowing the wearer to see properlyat a far-intermediate distance and an intermediate distance. In certainembodiments of the present invention, the lens may have verticalstability of vision in the upper far-intermediate distance zone and/orvertical stability of vision in the intermediate zone. In embodiments ofthe present invention that do not have a far-intermediate zone, theintermediate distance zone may have increased vertical stability ofvision (i.e., extend further vertically).

An additional far-intermediate distance region may be provided below thenear distance zone. In such an embodiment, this region may be referredto as the “lower” far-intermediate distance zone and thefar-intermediate distance region between the far distance region and theintermediate distance region may be referred to as the “upper”far-intermediate distance region. The upper and lower far-intermediatezones may have the same optical power. The lower far-intermediate zonemay be included in embodiments of the present invention to allow thepresbyopic wearer to see his or her feet or the floor more easily whenlooking downwards. This may provide additional safety when walking upand down stairs.

Embodiments of the present invention may include one or morediscontinuities between regions of the lens. Typically, embodiments ofthe present invention only include a single discontinuity. Thediscontinuities may be caused by a discontinuous surface or bydiscontinuous optical power between two different regions of the lens.The discontinuities may be caused by a step up or a step down in opticalpower. A discontinuity is defined by any change in a surface of a lensor in an optical power of the lens that results in a perceived imagebreak when looking through the lens. By way of example only, theinventors have fabricated a variety of lenses and have found that it isdifficult to perceive an image break when a lens has an optical powerdiscontinuity of less than approximately 0.10 D when the lens ispositioned at a distance from the eye consistent with how spectaclelenses are typically worn. However, optical power discontinuities largerthan approximately 0.10 D to 0.12 D can be visually detected by a wearerin most cases. Furthermore, such optical power discontinuities that canbe perceived by a wearer of the lens can be disturbing to the wearer'svision during certain visual tasks such as, for example, viewing acomputer screen. It should be noted that the optical power values statedabove for a discontinuity are only exemplary and a discontinuity isdefined as any change in a surface or optical power of a lens thatresults in the ability to perceive an image break when looking throughthe lens.

The inventors have further established that certain discontinuities aremore noticeable and/or disturbing than others. Embodiments of thepresent invention may therefore include one or more discontinuities thatare less noticeable and/or less disturbing. The inventors have foundthat a discontinuity between the far distance zone and the upperfar-intermediate distance zone of the lens is visually tolerated by auser far better than a discontinuity located within the intermediatedistance zone, the near distance zone, or between the intermediatedistance zone and the near distance zone. In addition, the inventorshave established that the narrower the width of a blend zone whichblends at least a portion of the discontinuity, the better the eyetransitions over the discontinuity due to the fact that the eyetransitions more quickly over any image break or blur created by theblend zone. Although this would seem to indicate that the discontinuityshould therefore not be blended, this must be balanced by the positivecosmetic effect of blending the discontinuity to create a nearlyinvisible discontinuity.

Embodiments of the present invention may comprise one or morediscontinuities, wherein a discontinuity may be caused by a step up inoptical power of +0.12 D or more Embodiments may have a singlediscontinuity which is at least partially blended by a blend zone havinga width less than approximately 2.0 mm or between approximately 1.0 mmand 0.5 mm. Blend zones of this width can be generated by diamondturning. However, in other embodiments of the present invention thediscontinuity is not blended. In embodiments of the present inventionthe discontinuity may be created by a step up in optical power of overapproximately +0.25 D and in most cases over approximately +0.50 D. Thestep up in optical power and thus the discontinuity is usually, but notalways, located between the far distance zone of the inventive lens andthe far-intermediate distance zone. Alternatively, when the lens doesnot have a far-intermediate distance zone, the discontinuity is usuallylocated between the far distance zone and the intermediate distance zoneof the lens. FIGS. 25 and 26 show such a step up in optical power priorto the start of the progressive optical power region according toembodiments of the present invention.

All embodiments of the present invention allow for the ability to havethree usable zones of optical power: a far distance zone, anintermediate distance zone, and a near distance zone. Embodiments of thepresent invention may also provide for the ability to have a fourthzone, an upper far-intermediate distance zone and, in some embodiments,a fifth zone, a lower far-intermediate distance zone. Embodiments of thepresent invention may:

-   -   a) Increase the length of the channel to allow for an additional        2 mm to 3 mm plateau of optical power to provide for upper        far-intermediate distance correction. Such an optical power zone        may be useful when using one's computer or looking to the edge        of one's desk. It should be noted that increasing the channel        length may not be possible depending on the vertical dimensions        of the eyeglass frame which will house the lens.    -   b) Increase the length of the channel to allow for an additional        2 mm to 3 mm plateau of optical power to provide for lower        far-intermediate distance correction. Such an optical power zone        may be useful when looking at one's feet or the floor when        climbing up or down stairs. It should be noted that increasing        the channel length may not be possible depending on the vertical        dimensions of the eyeglass frame which will house the lens.    -   c) Utilize one or more discontinuities. The one or more        discontinuities may be caused by one or more steps in optical        power, wherein a step is either a step up or a step down in        optical power. Because a discontinuity uses very little, if any,        lens real estate to step up or down the optical power, the        channel can be designed to allow for a plateau of optical power        without extending the length of the channel. It is important to        note that the larger the step in optical power, the more real        estate in the lens can be provided for an optical power plateau.        In embodiments of the invention, a plateau of optical power may        be provided after a discontinuity and provides for a        far-intermediate distance correction. This is accomplished        without adding to the length of the channel. FIG. 22 shows an        embodiment of the present invention having two plateaus of        optical power; 2230 and 2240 and FIG. 23 shows an embodiment of        the present invention having three plateaus of optical power:        2330, 2340, and 2350.    -   d) Keep the length of the channel the same, but ramp up the        optical power more quickly between the various zones of optical        power. It should be noted that this usually results in problems        with vision comfort and eye fatigue of the wearer.    -   e) Use a step down in optical power immediately below the near        distance zone to allow for a lower far-intermediate distance        zone. It should be noted that a lower far-intermediate distance        zone may only be possible if there is enough lens real estate        below the near distance portion of the lens.

FIG. 22 shows the optical power along the center vertical mid-line of anembodiment of the present invention including a progressive opticalpower region connecting the far distance zone to the near distance zone.The figure is not drawn to scale. The optical power in the far distancezone is shown as plano and is therefore represented by the x-axis 2210.The progressive optical power region begins at the fitting point of thelens 2220. Alternatively, the progressive optical power region may beginbelow the fitting point. Although the optical power of the progressiveoptical power region increases over the length of the channel, theprogressive optical power region may provide for two plateaus of opticalpower within the channel. The first plateau 2230 provides an upperfar-intermediate distance correction and the second plateau 2240provides an intermediate distance correction. Alternatively, theprogressive optical power region provides for a single plateau ofoptical power which provides either an intermediate distance correctionor a far-intermediate distance correction. The first plateau of opticalpower may have a vertical length along the channel between approximately1 mm and approximately 6 mm or between approximately 2 mm andapproximately 3 mm. However, in all cases, a plateau of optical powerhas a vertical length of at least approximately 1 mm. In cases with twoplateaus, after the first plateau of optical power the optical powercontributed by the progressive optical power region increases until asecond plateau of optical power. The second plateau of optical power mayhave a vertical length along the channel between approximately 1 mm andapproximately 6 mm or between approximately 2 mm and approximately 3 mm.After the second plateau of optical power the optical power contributedby the progressive addition region increases until the total neardistance optical power is reached at 2250. After the near distanceoptical power is achieved the optical power contributed by theprogressive optical power region may begin to decrease. If the opticalpower decreases to between approximately 20% to approximately 44% of theadd power in the near distance zone, a lower far-intermediate zone maybe provided.

FIG. 23 shows the optical power along the center vertical mid-line of anembodiment of the present invention including a progressive opticalpower region connecting the far distance zone to the near distance zone.The figure is not drawn to scale. The optical power in the far distancezone is shown as plano and is therefore represented by the x-axis 2310.The progressive optical power region begins at the fitting point of thelens 2320. Alternatively, the progressive optical power region may beginbelow the fitting point. Although the optical power of the progressiveoptical power region increases over the length of the channel, theprogressive optical power region may provide for three plateaus ofoptical power within the channel. The first plateau 2330 provides anupper far-intermediate distance correction, the second plateau 2340provides an intermediate distance correction, and the third plateau 2350provides a near distance correction. The first plateau of optical powermay have a vertical length along the channel between approximately 1 mmand approximately 6 mm or between approximately 2 mm and approximately 3mm. However, in all cases, a plateau of optical power has a verticallength of at least approximately 1 mm. After the first plateau ofoptical power the optical power contributed by the progressive opticalpower region increases until a second plateau of optical power. Thesecond plateau of optical power may have a vertical length along thechannel between approximately 1 mm and approximately 6 mm or betweenapproximately 2 mm and approximately 3 mm. After the second plateau ofoptical power the optical power contributed by the progressive opticalpower region increases until a third plateau of optical power. The thirdplateau of optical power may have a vertical length along the channelbetween approximately 1 mm and approximately 6 mm or betweenapproximately 2 mm and approximately 3 mm. After the near distanceoptical power is achieved at 2360 the optical power contributed by theprogressive optical power region may begin to decrease. If the opticalpower decreases to between approximately 20% to approximately 44% of theadd power in the near distance zone, a lower far-intermediate zone maybe provided.

FIG. 24 shows the optical power along the center vertical mid-line of anembodiment of the present invention including a mostly spherical powerregion, a discontinuity, and a progressive optical power regionconnecting the far distance zone to the near distance zone. The figureis not drawn to scale. The optical power in the far distance zone isshown as plano and is therefore represented by the x-axis 2410. Theprogressive optical power region begins at or near the fitting point ofthe lens 2420. The discontinuity 2430 may be caused by the mostlyspherical power region, which causes a step in optical power, andcontributes an optical power 2440. The progressive optical power regionmay start above the discontinuity. In this case, the start of theprogressive optical power region may be located by measuring the opticalpower in the far distance zone and then locating an area or region ofthe lens above the discontinuity where the optical power of the lensbegins to gradually increase in plus optical power or reduce in minusoptical power. The difference between the optical power just before thediscontinuity and just after the discontinuity is referred to as a “stepin optical power”. A “step up in optical power” occurs if the opticalpower increases from before the discontinuity to after thediscontinuity. A “step down in optical power” occurs if the opticalpower decreases from before the discontinuity to after thediscontinuity. Thus, if the progressive optical power region startsabove the discontinuity, immediately before the discontinuity the totaloptical power in the lens is the optical power of the progressiveoptical power region and the far distance zone and immediately after thediscontinuity the total optical power in the lens is the optical powercaused by the step in optical power and the optical power of theprogressive addition region and the far distance zone. Alternatively,the progressive optical power region may start below the discontinuitysuch that immediately before the discontinuity the total optical powerin the lens is the far distance optical power and after thediscontinuity, once the progressive optical power region starts, thetotal optical power in the lens is the optical power caused by the stepin optical power and the optical power of the progressive additionregion and the far distance zone. The progressive optical power regionmay begin immediately after the discontinuity. Alternatively, theprogressive optical power region may begin 1 or more millimeters fromthe discontinuity thereby creating a plateau of optical power 2450 thatmay be useful for intermediate distance viewing or upperfar-intermediate distance viewing. In some embodiments of the presentinvention the progressive optical power region may have a negativeoptical power 2460 such that the region decreases the total opticalpower in the lens before having a positive optical power that increasesthe total optical power in the lens. For example, the optical powercaused by the step in optical power may be higher than the optical powerneeded for proper far-intemiediate distance viewing. In this case, aportion of the progressive optical power region at and immediately afterthe discontinuity may decrease the optical power of the lens to providea proper upper far-intermediate distance correction. The progressiveoptical power region may then increase in optical power to provide aproper intermediate distance correction 2470. The optical power of theprogressive optical power region may further increase until the fullnear distance optical power 2480 after which it may begin to decreaseagain. Thus, the mostly spherical power region and the progressiveoptical power region may each have an incremental add power whichtogether provide the total add power of the lens. If the optical powerdecreases to between approximately 20% to approximately 44% of the addpower in the near distance zone, a lower far-intermediate zone may beprovided.

In embodiments of the present invention in which the progressive opticalpower region begins above the discontinuity, the optical powercontributed by the progressive optical power region may initially bezero or negative. The discontinuity may be caused by a step in opticalpower. The optical power caused by the step in optical power may beapproximately equal to the optical power needed for proper intermediatedistance correction or for far-inteiinediate distance correction.Therefore, if the initial optical power contributed by the progressiveoptical power region is zero, the combined optical power after thediscontinuity will be the proper intermediate distance correction orfar-intermediate distance correction. Similarly, the optical powercaused by the step in optical power may be larger than the optical powerneeded for proper intermediate distance correction or forfar-intermediate distance correction. Therefore, if the initial opticalpower contributed by the progressive optical power region is negative,the combined optical power after the discontinuity will be the properintermediate distance correction or far-intermediate distancecorrection. In either case, if the progressive optical power regioninitially contributed a positive optical power, the combined opticalpower after the discontinuity may be too strong. This was proven to bethe case in FIGS. 16-20. Furthermore, it should be noted that if thestep in optical power causes a higher optical power than needed forproper intermediate distance correction or for far-intermediate distancecorrection, a lower add power progressive optical power region may beused thereby improving the optical characteristics of the lens. Itshould be noted that the lower the progressive optical power region'soptical power, the less unwanted astigmatism and distortion will beadded to the final lens.

Alternatively, in embodiments of the present invention in which theprogressive optical power region begins above the discontinuity, theoptical power contributed by the progressive optical power region mayinitially be positive. In these embodiments, the optical power caused bythe step in optical power is reduced to be less than the optical powerneeded for proper intermediate distance correction or for properfar-intermediate distance correction. Therefore, if the initial opticalpower contributed by the progressive optical power region is positive,the combined optical power after the discontinuity will be the properintermediate distance correction or far-intermediate distancecorrection. However, it should be noted that in this embodiment theunwanted astigmatism and distortion are greater in the final lens thanan embodiment in which the mostly spherical region's optical power isequal to or greater than the optical power contributed by theprogressive optical power region.

FIG. 25 shows the optical power along the center vertical mid-line of anembodiment of the present invention including a mostly spherical powerregion, a discontinuity, and a progressive optical power regionconnecting the far distance zone to the near distance zone. The figureis not drawn to scale. The optical power in the far distance zone isshown as plano and is therefore represented by the x-axis 2510. Thediscontinuity 2520 may be located below the fitting point 2530, forexample, approximately 3 mm below the fitting point. The discontinuitymay be caused by the mostly spherical power region, which causes a stepin optical power, and contributes an optical power 2540. The progressiveoptical power region may start at a portion of the mostly sphericalpower region, for example, immediately after the discontinuity orshortly thereafter at 2550. The mostly spherical power region may havean “aspheric portion” 2560 within approximately 3 mm to 5 mm of thediscontinuity. After this portion, the mostly spherical power region maybe substantially spherical. The combination of the progressive opticalpower region's optical power and the mostly spherical power region'saspheric portion's optical power may form a combined progressive opticalpower region having an optical power that increases immediately afterthe discontinuity in a mostly continuous manner as opposed to a sharpstep up in optical power. The net optical effect is that the step inoptical power is less than the full optical power 2570 provided by themostly spherical power region. The aspheric portion and the progressiveoptical power region allow the full optical power of the mostlyspherical power region to be achieved gradually after the discontinuity.The aspheric portion may provide a proper upper far-intermediatedistance correction 2580. Alternatively, the progressive optical powerregion may contribute additional optical power to provide the properupper far-intermediate distance correction. The progressive opticalpower region may then increase in optical power to provide a properintermediate distance correction 2585. Alternatively, a properfar-intermediate distance correction may not be provided. The opticalpower of the progressive optical power region may further increase untilthe full near distance optical power 2590 after which it may begin todecrease again. Thus, the mostly spherical power region and theprogressive optical power region may each have an incremental add powerwhich together provide the total add power of the lens. In embodimentsof the present invention a lower far-intermediate distance correction2595 may be provided by a step down in optical power after the neardistance zone. Alternatively, the lower far-intermediate distance zonemay be provided by the progressive optical power region contributingnegative optical power which decreases the optical power in the lens.

FIG. 26 shows the optical power along the center vertical mid-line of anembodiment of the present invention including a mostly spherical powerregion, a discontinuity, and a progressive optical power regionconnecting the far distance zone to the near distance zone. The figureis not drawn to scale. The optical power in the far distance zone isshown as plano and is therefore represented by the x-axis 2610. Thediscontinuity 2620 may be located below the fitting point 2630 betweenthe far distance zone and the upper far-intermediate distance zone 2640.Alternatively, the discontinuity may be located below the fitting pointbetween the far distance zone and the intermediate distance zone 2650.The discontinuity may be caused by the mostly spherical power region,which causes a step in optical power, and contributes an optical power2660. The step up in optical power may be equal to the optical powerneeded for far-intermediate distance correction. Alternatively, the stepup in optical power may be equal to the optical power needed forintermediate distance correction. The progressive optical power regionmay start at a portion of the mostly spherical power region, forexample, immediately after the discontinuity or shortly thereafter at2670. If the progressive optical power region begins below thediscontinuity, a plateau of optical power may then be provided foreither the upper far-intermediate distance zone or for the intermediatedistance zone. The progressive optical power region continues until thefull near distance optical power 2680 after which it may contributenegative optical power that decreases the optical power in the lens.Thus, the mostly spherical power region and the progressive opticalpower region may each have an incremental add power which togetherprovide the total add power of the lens. If the optical power decreasesto between approximately 20% to approximately 44% of the add power inthe near distance zone, a lower far-intermediate zone may be provided.In some embodiments of the present invention, the lens may includeplateaus of optical power for any of the distance zones.

In an embodiment of the present invention the lens may provide +2.00 Dnear add power. The lens may include a buried mostly spherical powerregion having an optical power of +1.00 D (i.e., the mostly sphericalpower region has an incremental add power) that is aligned so that thetop edge of the mostly spherical power region is aligned approximately 3mm below the fitting point of the lens. The lens may have a progressiveoptical power surface having a progressive optical power region locatedon the convex external surface of the lens. Alternatively, theprogressive optical power surface could be located on the concavesurface of the lens, split between both external surfaces of the lens,or buried within the lens. The progressive optical power region has aninitial optical power of zero which increases to a maximum optical powerof +1.00 D (i.e., the progressive optical power region has anincremental add power). The progressive optical power region is alignedso that the start of its channel which has zero optical power beginsapproximately 10 mm below the fitting point of the lens. In other words,the progressive optical power region is aligned so that the start of itschannel is approximately 7 mm below the discontinuity caused by the stepup in optical power caused by the buried spherical power region. In thisembodiment, there is no far-intermediate distance zone found in thelens. However, the intermediate distance zone has a minimum ofapproximately 7 mm of vertical stability of vision which is far greaterthan any PAL lens commercially available. As can be readily understood,the combined optical power of the progressive optical power and themostly spherical power region does not begin until after approximately 7mm below the top edge of the mostly spherical power region. Thus, theoptical power from approximately 3 mm below the fitting to approximately10 mm below the fitting point is the +1.00 D optical power which isprovided by the mostly spherical power region. This optical power is 50%of the near distance add power and therefore provides properintermediate distance correction.

In still another embodiment of the present invention, the lens mayprovide +2.50 D near add power. The lens may have a mostly sphericalpower region having an optical power of +1.25 D (i.e., the mostlyspherical power region has an incremental add power) which is freeformed on the concave back toric/astigmatic correcting external surfaceof the lens that is aligned so that the top edge of the mostly sphericalpower region is approximately 4 mm below the fitting point of the lens.The lens may have a progressive optical power region located on thefront convex surface of the lens having an initial optical power of zerowhich increases to a maximum optical power of +1.25 D (i.e., theprogressive optical power region has an incremental add yower). Theprogressive optical power region is aligned so that the start of itschannel begins approximately 10 mm below the fitting point of the lens.In other words, the progressive optical power region is aligned so thatthe start of its channel is approximately 6 mm below the discontinuitycaused by the step up in optical power caused by the buried sphericalpower region. In this inventive embodiment, there is no far-intermediatedistance zone found in the inventive lens. However, the intermediatedistance zone has a minimum of approximately 6 mm of vertical stabilityof vision which is far greater than any PAL lens commercially available.As can be readily understood, the combined optical power of theprogressive optical power and the mostly spherical power region does notbegin until after approximately 6 mm below the top edge of the mostlyspherical power region (the top edge of the mostly spherical powerregion being the location of the discontinuity). Thus, the optical powerfrom approximately 4 mm below the fitting to approximately 10 mm belowthe fitting point is the +1.25 D optical power which is provided by themostly spherical power region. This optical power is 50% of the neardistance add power and therefore provides proper intermediate distancecorrection.

In an embodiment of the present invention the lens may provide +2.25 Dnear add power. The lens may include a buried mostly spherical powerregion having an optical power of +0.75 D (i.e., the mostly sphericalpower region has an incremental add power) that is aligned so that thetop edge of the mostly spherical power region is aligned approximately 3mm below the fitting point of the lens. The lens may have a progressiveoptical power surface having a progressive optical power region locatedon the convex external surface of the lens. Alternatively, theprogressive optical power surface could be located on the concavesurface of the lens, split between both external surfaces of the lens,or buried within the lens. The progressive optical power region has aninitial optical power of zero which increases to a maximum optical powerof +1.50 D (i.e., the progressive optical power region has anincremental add power). The progressive optical power region is alignedso that the start of its channel which has zero optical power beginsapproximately 7 mm below the fitting point of the lens. In other words,the progressive optical power region is aligned so that the start of itschannel is approximately 4 mm below the discontinuity caused by the stepup in optical power caused by the buried spherical power region. In thisembodiment, there is a far-intermediate distance zone found in the lens.The far-intermediate distance zone has a minimum of approximately 4 mmof vertical stability of vision. No commercially available PAL has afar-intermediate distance zone or a far-intermediate distance zonehaving such a long vertical stability of vision. As can be readilyunderstood, the combined optical power of the progressive optical powerregion and the mostly spherical power region does not begin until afterapproximately 4 mm below the top edge of the mostly spherical powerregion. Thus, the optical power from approximately 3 mm below thefitting to approximately 7 mm below the fitting point is the +0.75 Doptical power which is provided by the mostly spherical power region.This optical power is 33.33% of the near distance add power andtherefore provides proper far-intermediate distance correction.

It should be pointed out that the above embodiments are provided asexamples only and are not meant to limit the distances from the fittingpoint for the alignment of the progressive optical power region or themostly spherical power region. In addition the optical powers given inthe examples are also not meant to be limiting. Further, the location ofa region being on the surface of the lens, split between surfaces of thelens, or buried within the lens should not be construed as limiting.Finally, while certain embodiments above may teach the absence of afar-intermediate distance zone, the far-intermediate distance zone canbe included by altering the alignment and/or optical powers provided byeach region.

As mentioned above, in embodiments of the present invention, a firstoptical power region having a first incremental add power may be inoptical communication with a second optical power region having a secondincremental add power such that the two incremental add powers areoptically aligned to provide a proper near distance correction for awearer. The incremental add powers may be provided refractively ordiffractively. In other words, the optical power regions may be part ofa refractive optic or a diffractive optic. The first optical powerregion may be a mostly spherical power region and the second opticalpower region may be a progressive optical power region. The mostlyspherical power region may thus have a mostly spherical incremental addpower and the progressive optical power region may thus have aprogressive incremental add power.

In embodiments of the present invention, the mostly spherical powerregion may be on a surface of an ophthalmic lens or buried within theophthalmic lens. The mostly spherical incremental add power may be in arefractive power region that generates optical power in a refractivemanner. Alternatively, the mostly spherical incremental add power may bein a diffractive optical power region that generates optical power in adiffractive manner. For both refractive and diffractive optical powerregions, optical power is generated by an optical interface between afirst optical material and a second optical material having differentindices of refraction. A refractive power region may be a section of asurface of a sphere where the optical power is defined by: φ=(n₂−n₁)/R,where φ is the optical power in diopters of the refractive power region,n₂ is the index of refraction of the first optical material, n₁ is theindex of refraction of the second optical material, and R is the radiusof the sphere. The refractive power region is comprised of a thickness,an index of refraction, and a curvature change.

A diffractive optical power region may be a phase-wrapped, surfacerelief diffractive structure comprised of concentric rings of theappropriate blaze profile. Such a structure is well-known in the art.The optical power of such a diffractive optical power region is definedby: r_(i)=[(2iλ)/φ]^(1/2), where r_(i) is the radius of the i^(th) ring(i=1, 2, 3, . . . ), λ is the design wavelength of the diffractiveoptical power region, and φ is the optical power in diopters of thediffractive optical power region. While the radii of the rings determinethe optical power of the diffractive optical power region, the height,d, of the surface relief diffractive structure determines the fractionof incident light brought to focus (i.e., the diffraction efficiency ofthe diffractive optical power region). Maximum diffraction efficiency isachieved when the phase retardation of the diffractive optical powerregion is an integer number of wavelengths as defined by: (n₂−n₁)d=mλ,where n₂ is the index of refraction of the first optical material, n₁ isthe index of refraction of the second optical material, d is the heightof the diffractive structure, λ is the design wavelength of thediffractive optical power region, and m is an integer (m=1, 2, 3, . . .).

In an embodiment of the present invention, a first multifocal optichaving a refractive progressive optical power region may be provided.The refractive progressive optical power region may have an incrementaladd power of +1.00 D, though any add power is possible. The firstmultifocal optic may be comprised of CR39 resin (trademarked by PPG) andhave a refractive index of approximately 1.50, by way of example only.The first multifocal optic may be cured (by way of example only, bythermal casting) onto the surface of a second multifocal optic to form acomposite lens. The second multifocal optic may have at least one mostlyspherical power region having an incremental add power. The secondmultifocal optic may be a lens, a lens wafer, a finished lens blank, ora semi-finished lens blank. The second multifocal optic may be comprisedof a cured polymer such as, by way of example only, Mitsui's MR10 whichhas a refractive index of approximately 1.67. The second multifocaloptic may have at least one multifocal surface capable of generatingmore than one optical power. The multifocal surface may be on theoutside of the second multifocal optic prior to being covered by thefirst multifocal optic.

The multifocal optic can be one of (by way of example only) a refractiveexecutive bifocal, a refractive lined FT 28, a refractive FT 35, arefractive curve top 28, a refractive curve top 35, a refractive 7×35trifocal, a refractive ultex bifocal, a refractive round 22 bifocal, anon-refractive (i.e., diffractive) optical power region having a surfacerelief diffractive pattern that is designed to provide a specificpositive diopter optical power, or any other multifocal optic having amostly spherical incremental add power region. The second multifocaloptic may have any combination of optical powers.

It should be noted that in most embodiments of the present invention themostly spherical power region having a first incremental add power isphysically separated (i.e., spaced apart) from and is in opticalcommunication with the progressive optical power region that has asecond incremental add power region. The mostly spherical power regionmay be a buried refractive or diffractive optical power region. In otherembodiments of the present invention, a first incremental add power ispart of a refractive optical power region and is optically aligned andin optical communication with, but not spaced apart from (i.e., not inphysical contact with) a second incremental add power that is part of adiffractive optical power region. In embodiments of the presentinvention, the mostly spherical power region's horizontal diameter(regardless of whether the region is diffractive or refractive) is widerthan the reading zone width of the lens as defined by the progressiveoptical power region.

In most, but not all cases, the diffractive optical power region mayprovide an optical power that is within the range of +0.50 D and +1.50D, though any optical power is possible. Those skilled in the art canreadily design such a diffractive optic. It should be further pointedout that the optical power at or near the peripheral outer edge ofeither the diffractive optical power region or the lined boundary of themostly spherical incremental add power region can be blended so as tohide the peripheral edge discontinuity of the second multifocal opticwithin the composite lens. Such a blend can be that of a optical powerblend, optical efficiency blend, or a combination of both.

In certain embodiments of the present invention, the second multifocaloptic may be provided as a semi-finished lens blank having a burieddiffractive optical power region that contributes an incremental addpower of +1.00 D within the semi-finished blank whereby the lens blankis finished on one external surface and is unfinished on the otheropposing surface of the optic. However, it should be pointed out thatthe incremental add power of the diffractive optical power region can bewithin the range of +0.25 D to +1.50 D. The first multifocal optic thatcomprises a refractive incremental add power region may be cast andcured onto the surface of the second multifocal optic that has thediffractive incremental add power region in order to form the compositeoptic whereby the refractive incremental add power region is spacedapart (i.e., physically separated) from the diffractive incremental addpower region however both refractive and diffractive incremental addpower regions are aligned to be in optical communication with oneanother.

In this embodiment, the diffractive incremental add power region isburied within the final composite lens, lens blank, or semi-finishedlens blank. In such an embodiment, the composite lens may have anexternal front surface having a refractive progressive optical powerregion, a buried diffractive optical power region, and an unfinishedexternal back surface capable of being free formed or surfaced andpolished at a latter date. It should be noted that in certainembodiments of the invention the buried diffractive optical power regionis located within a semi-finished lens blank such that during the stepof free forming the semi-finished lens blank a refractive progressiveoptical power region is added and aligned properly to the semi-finishedlens blank. This is done in such a manner that the buried diffractiveoptical power region is aligned and in proper optical communication withthe newly added (i.e., free formed) refractive progressive optical powerregion. It should be noted that in another embodiment of the presentinvention the buried diffractive optical power region is located withinan unfinished lens blank such that during the step of free forming theunfinished lens blank a refractive progressive optical power region isadded and aligned properly to the unfinished lens blank. This is done insuch a manner that the buried diffractive optical power region isaligned and in proper optical communication with the newly added (i.e.,free formed) refractive progressive optical power region. The burieddiffractive optical power region contributes optical power to thecomposite lens due to the index of refraction difference between thefirst multifocal optic material composition and the second multifocaloptic material composition.

It is to be understood that while in this specific embodiment of thepresent invention the first multifocal optic comprises a material havingan index of refraction of approximately 1.50 and the second multifocaloptic comprises a material having an index of refraction ofapproximately 1.67, the material for each optic may be reversed and forthat mater can be of any index of refraction so long as the twomaterials have two different indices of refraction.

Embodiments of the present invention may be described in terms of amostly spherical power region. However, it is to be understood thatsince a diffractive optical power region is a type of mostly sphericalincremental add power region, these embodiments also describeembodiments of the present invention that include a diffractive opticalpower region. Thus, the size, shape, and optical design of thediffractive optical power region may be the same as the size, shape, andoptical design of a mostly spherical power region as described byembodiments of the present invention. Similarly, the alignment of thediffractive optical power region relative to the progressive opticalpower region may be the same as the alignment of a mostly sphericalpower region relative to a progressive optical region as described byembodiments of the present invention.

In another embodiment of the present invention, a lined bifocal may bethe second multifocal optic. The multifocal surface of the lined bifocalmay be buried within the composite lens. In this embodiment, therefractive curves of the lined bifocal may be designed to allow for theproper additive power needed given the index of refraction of thematerial used for the second multifocal optic and the index ofrefraction of the material used for the first multifocal optic. In most,but not all cases, the add power contribution (i.e., the incremental addpower) of the second multifocal optic may be one of +0.25 D, +0.50 D,+0.75 D, +1.00 D, +1.25 D, and in some cases +1.50 D or any opticalpower within the range of +0.25 D and +1.50 D. In most, but not allcases, the far distance optical power of the second multifocal optic iszero optical power. The optical power contribution of the refractiveprogressive optical region on the first multifocal optic may provide thefar distance optical power correction for the wearer and an incrementaladd power contribution that is in most cases, but not all, one +0.75 D,+1.00 D, +1.25 D, and +1.50 D or any optical power within the range of+0.75 D and +1.50 D.

In still other embodiments of the present invention, the external backsurface of the composite lens may be finished. When the external backsurface of the composite lens is finished, the back surface may providethe needed posterior curvatures to provide at least part of thecorrection of the wearer's far distance, intermediate distance, and/ornear distance vision. Thus, the composite lens may be capable ofcorrecting the wearer's refractive error such as the wearer'sastigmatism, hyperopia, myopia, and/or presbyopia. When the back surfaceis unfinished (e.g., the second multifocal optic is a semi-finishedblank) the composite lens will not have a final finished optical power.It should be pointed out that it is possible to freeform the appropriaterefractive curvature on one or both of the external surfaces of thelens.

In another embodiment of the present invention, a thin optical waferhaving a multifocal surface may be buried within a cavity filled with anuncured resin to form a composite lens when the resin is cured. Thus,the resin may form both external surfaces of the composite lens once theresin is cured. The multifocal surface may generate an optical powereither refractively or diffractively. The resin will have an index ofrefraction that is different than the index of refraction of the thinoptical wafer. One of the surfaces of the uncured resin, once cured, mayform a refractive progressive optical power region (or for that materany desired refractive optical power region) having an external surfacecurvature. The resin may be cured by one of a thermal cure, a photo cure(visible or invisible), or a combination of a photo cure and a thermalcure, for example. The optical wafer may be held in position, by way ofexample only, by a gasket used in the casting process.

In another embodiment of the present invention, a first thin optic mayhave a progressive optical power region on its surface. This first thinoptic can be preformed or can be formed in situ by way of casting ormolding. Such casting or molding methods are well known and can be athermal cure, a photo cure, or a combination of both. The first thinoptic will have a known index of refraction. The first thin optic may beformed on top of a different thin layer of a prefabricated opticalmaterial (a second optical perform) having a different index ofrefraction from the thin optic to form a composite optic. When both thefirst thin optic and the second optical perform are both preformed theymay be adhesively bonded to one another. When the first thin optic isformed in situ it can be cast directly onto the second optical perform.The second preform may have a mostly spherical power region thatprovides an incremental add power region that generates optical powereither refractively or diffractively. The newly formed composite opticmay be adhesively bonded to a thicker non-finished lens blank to form acomposite lens having an external surface having a refractiveprogressive optical power region, a buried mostly spherical powerregion, and an unfinished external surface capable of being finished byfabrication techniques known in the art.

In most embodiments of the present invention, but not all, the opticalperform that comprises the mostly spherical incremental add power regionmay be used as an integral consumable back mold that is placed in theback of an optical gasket used for casting ophthalmic lenses. The term“integral consumable” is used to denote that the lens or optic is usedboth as a mold to form the back of the composite lens, but also that thelens or optic is consumed and becomes bonded to the portion of thecomposite lens being cured within the mold, thus becoming an integralpart of the final composite lens. The front mold may be provided by wayof a glass or metal mold that is utilized in casting ophthalmic lenses.The cavity formed between the front mold and the back consumable moldmay be filled with an optical resin having the proper index ofrefraction and cured. The curing may be one of a thermal curing, a lightcuring, or a combination of both depending upon the initiator needed andthe material to be cured, for example. In this embodiment of theinvention the surface of the optical perform comprising the mostlyspherical incremental add power region is placed facing the uncuredresin layer having a different index of refraction which will then bondto the surface of the optical perform comprising the mostly sphericalincremental add power region. Upon curing, this interface will form aninterface where the two different indices of refraction of the materialsmeet. This index of refraction mismatch allows for the appropriateburied incremental add power to be provided.

In embodiments of the present invention, the molding technique justdescribed may allow for the fabrication of either semi-finished orfinished lens blanks. When casting the composite lens as a finished lensblank, the consumable back mold may be prefabricated with theappropriate toric curves on its external back surface so as to correctfor the wearer's astigmatic refractive error. The consumable back moldmay then be rotated within the gasket to allow for aligning theastigmatic axis relative to the front surface mold that forms theprogressive optical power region's curvature in the composite lens. Thetechnique of setting the axis of astigmatic correction is well known inthe art of finished ophthalmic lens casting.

In still another embodiment of the present invention, a front integralconsumable mold being made of optical plastic material (also that of anoptical perform) may be used. The front integral consumable mold, oroptical perform, may be preformed having a refractive progressiveoptical power region curvature on its external surface and a sphericalpower region that generates optical power either refractively ordiffractively on its internal back surface. In this case, a glass ormetal mold may be used on the back to form the cavity which is to befilled with a resin and then cured to form a composite lens. The frontconsumable mold in this case may become integral with the cured resinoptic that is formed. Following this, the back of the composite lenscould be free formed or ground and polished. Also, as discussed before,the back surface of the composite lens could be molded upon curing intoa finished surface that provides the necessary toric curvature needed tocorrect the astigmatism of the intended wearer and/or provide the properspherical power needed for the wearer's far distance optical powercorrection as well as the wearer's near distance optical powercorrection. When an optical perform is used as a consumable mold thesurface that faces the uncured resin may be the buried incremental addpower region (which can be refractive or diffractive). Furthermore, theindices of refraction of the optical preform and the resin or newlycured layer are of different values.

FIGS. 29A-29D show methods of manufacturing a composite semi-finishedlens blank according to embodiments of the present invention. FIG. 29Ashows a method of manufacturing a composite lens including casting apreformed diffractive multifocal optic having a diffractive opticalpower region and having a known index of refraction, followed by castinga layer of a different index of refraction that comprises theprogressive optical power region's curvature on top of the diffractivemultifocal optic. In this embodiment, the diffractive optical powerregion is configured to be that of the mostly spherical incremental addpower region. FIG. 29B shows the same method of manufacturing as FIG.29A with the exception of using a different front casting ophthalmicmaterial. FIG. 29C shows a method of manufacturing a composite lensincluding encapsulating a preformed diffractive multifocal optic (alsoreferred to as a preformed optical insert) having a known index ofrefraction and a diffractive optical power region between a frontprogressive optical power region and a back additional layer ofophthalmic material having a different index of refraction whereby thematerial of the front progressive optical power region and the backadditional layer are the same, however the material of the diffractivemultifocal optic is different. FIG. 29D shows the same method ofmanufacturing as FIG. 29C with the exception of the diffractivemultifocal optic material being cast from a different ophthalmicmaterial (such as a different material manufacturer) than thediffractive multifocal optic in FIG. 29C. It should be further pointedout that the semi-finished lens blank as illustrated herein can beeither surfaced or free formed to be that of a finished lens or afinished lens blank. In addition, the lens can be made by being fullymolded to the final finished lens shape and design by using theappropriate resin, mold or molds, and optical perform combinations.

Table I is a listing of various ophthalmic materials, any two of whichcan be utilized to make the composite lens provided the two materialsare either compatible and will bond to one another or a coating is usedto promote adhesion between the two materials.

TABLE I Material Ref. Index Abbe Value Supplier CR39 1.498 55 PPGNouryset 200 1.498 55 Great Lakes Rav-7 1.50 58 Evergreen/Great LakesCo. Trivex 1.53 44 PPG MR-8 1.597 41 Mitsui MR-7 1.665 31 Mitsui MR-101.668 31 Mitsui MR-20 1.594 43 Mitsui Brite-5 1.548 38 Doosan Corp.(Korea) Brite-60 1.60 35 Doosan Corp. (Korea) Brite-Super 1.553 42Doosan Corp. (Korea) TS216 1.59 32 Tokuyama Polycarbonate 1.598 31 GE

In certain embodiments of the invention a blend zone transitions theoptical power between at least a portion of the mostly spherical powerregion and the far distance zone. FIGS. 27A-27C show embodiments of thepresent invention having a blend zone 2710 with a substantially constantwidth located at or below a fitting point 2720. FIGS. 28A-28C showsembodiments of the present invention having a blend zone 2810 includinga portion with a width of substantially 0 mm (thereby providing atransition in this portion similar to a lined bifocal) located at orbelow a fitting point 2820. FIG. 27A and FIG. 28A show the top edge ofthe blend zone located at the fitting point. FIG. 27B and FIG. 28B showthe top edge of the blend zone located 3 mm below the fitting point.FIG. 27C and FIG. 28C show the top edge of the blend zone located 6 mmbelow the fitting point. Portions of blend zone 2710 and 2810 may beless than approximately 20 mm wide and may be between approximately 0.5mm wide and approximately 1.0 mm wide. It should be noted, thatembodiments of the present invention contemplate using a blend zonehaving a width between approximately 0.1 mm and approximately 1.0 mm.FIG. 28A further shows a central region of the blend zone correspondingto the location of the fitting point that has a width betweenapproximately 0.1 mm and approximately 0.5 mm. FIG. 28C shows blend zone2810 reducing in width to having no blend in the central region of theblend zone.

The mostly spherical power region and the far distance zone each have anoptical power that may be defined by a specific optical phase profile.To create a blend zone of a given width, a phase profile is generatedthat, in certain embodiments of the present invention, matches the valueand first spatial derivative of the phase profile of a first opticalpower region at the start of the blend zone and matches the value andfirst spatial derivative of the phase profile of a second optical powerregion at the end of the blend zone. In other embodiments of theinvention the start and end of the blend zone phase profile match thevalue as well as the first and second spatial derivatives of the phaseprofiles of the first and second optical power regions, respectively. Ineither case, the phase profile of the blend zone may be described by oneor more mathematical functions and/or expressions that may include, butare not limited to, polynomials of second order or higher, exponentialfunctions, trigonometric functions, and logarithmic functions. Incertain embodiments of the present invention the blend zone isdiffractive, in other embodiments of the present invention the blendzone is refractive and in still other embodiments of the presentinvention the blend zone has both refractive and diffractive sub-zones.

In some embodiments of the present invention in order for the lens toprovide high quality vision, the width of the blend zone must be quitenarrow. The blend zone must be narrow to allow the wearer's eye totraverse the blend zone quickly as the wearer's line of sight switchesbetween a far distance focus and an intermediate distance or neardistance focus. For example, the width of the blend zone may be lessthan approximately 2.0 mm, less than approximately 1.0 mm, or less thanapproximately 0.5 mm. Fabrication of such a narrow blend zone is verydifficult using conventional ophthalmic lens fabrication techniques. Forexample, current state-of-the-art single point, free-forming ophthalmicsurface generation only permits blend zones having a width in excess ofapproximately 0.5 mm. Furthermore, these methods provide little or nocontrol over the exact shape of the blend zone profile. The generationof conventional glass mold tooling for casting lenses from liquidmonomer resins is also limited, as glass cannot be single point machinedand must be worked with a grinding process where all fine surfacefeatures would be lost.

Currently, the only method available to generate lenses with a narrowblend zone having a known and well-controlled profile in an economicallyfeasible manner is the single point diamond turning of metal lens molds.In such a method the diamond tooling equipment is outfitted with eitherslow or fast tool servo capabilities, both of which are well known inthe art. Such molds can be generated, by way of example only, inmaterials such as electrolytic Ni or CuNi and may be used in either aliquid monomer resin casting process or a thermoplastic injectionmolding process.

Each of the above embodiments can be fabricated using diamond turning,free forming, surface-casting, whole-lens casting, laminating, ormolding (including injection molding). It has been found that inembodiments without a blend zone, diamond turning provides for thesharpest discontinuity and the best fidelity. In most, but not allcases, molds are diamond turned from metal such as, by way of exampleonly, nickel coated aluminum or steel, or copper nickel alloys.Fabrication methods or techniques needed to produce the steps in opticalpower are known in the industry and consist, by way of example only, ofdiamond turning molds or inserts and then casting or injection moldingthe lens, diamond turning the actual lens, and free forming.

In an embodiment of the present invention, by utilizing state-of-the-artfree-forming fabrication techniques it is possible to place the toricsurface that corrects the wearer's astigmatic refractive error on thesame surface of the lens as the mostly spherical power region. Whenthese two different surface curves are generated by free forming it isthen possible to place the progressive optical power region on theopposite surface of the lens. In this case the progressive optical powerregion is molded and pre-formed on one surface of the semi-finishedblank and the combined astigmatic correction and spherical power regionis provided by way of free-forming the opposite unfinished surface ofthe semi-finished blank.

In some embodiments of the present invention, the mostly spherical powerregion is wider than the narrowest portion of the channel bounded by anunwanted astigmatism that is above approximately 1.00 D. In otherembodiments of the present invention, the mostly spherical power regionis wider than the narrowest portion of the channel bounded by anunwanted astigmatism that is above approximately 0.75 D.

In some embodiments of the present invention the mostly spherical powerregion may be substantially spherical or may be aspheric as well; forexample, to correct for astigmatism. The mostly spherical power regionmay also have an aspheric curve or curves placed to improve theaesthetics of the lens or to reduce distortion. In some embodiments ofthe present invention, the inventive multifocal lens is static. In otherembodiments of the present invention, the inventive multifocal lens isdynamic and the mostly spherical power region is produced dynamicallyby, for example, an electro-active element. In some embodiments of thepresent invention, the mostly spherical power region is an embeddeddiffractive element such as a surface relief diffractive element.

Embodiments of the present invention contemplate the production ofsemi-finished lens blanks where one finished surface comprises themostly spherical power region, far distance zone and blend zone, and theother surface is unfinished. Also contemplated is the production ofsemi-finished lens blanks where one finished surface comprises theprogressive optical power region, and the other surface is unfinished.Also contemplated is that for certain prescriptions a finished lensblank is produced. It should also be noted that optimizing theprogressive optical power region relative to the mostly spherical powerregion to optimize the level of unwanted astigmatism, the channellength, and the channel width is also contemplated. In addition, it iscontemplated to optimize the blend zone, if desired, to further reducethe unwanted astigmatism found in the blend zone. Furthermore, any lensmaterials may be used whether plastic, glass, resin, or a composite.Also contemplated is the use of any optically useful index ofrefraction. All coatings and lens treatments that would normally be usedon ophthalmic lenses such as, by way of example only, a hard scratchresistant coating, an anti-refraction coating, a cushion coating, and aself-cleaning Teflon coating may be used. Finally, embodiments of thepresent invention may be fabricated by techniques known in the artincluding, but not limited to, surfacing, free-forming, diamond turning,milling, stamping, injection molding, surface casting, laminating,edging, polishing, and drilling.

Embodiments of the present invention may be used to produce contactlenses and spectacle lenses.

In order to more clearly show the superiority of the inventivemultifocal lens over conventional state-of-the-art PALs, an embodimentof the present invention was compared to two state-of-the-art PALs.Measurements of the lenses were taken from a Visionix VM-2500™ lensmapper, trademarked by Visionix. One of the state-of-the-art PALs is aVarilux Physio™ lens, trademarked by Varilux, having approximately +2.00D add power. The other state-of-the-art PAL is a Varilux Ellipse™ lens,trademarked by Varilux, which has a short channel design andapproximately +2.00 D add power. As can be seen in Table II, the Physiolens has a maximum unwanted astigmatism of 1.68 D, a channel width of10.5 mm, and a channel length of 17.0 mm. The Ellipse lens has a maximumunwanted astigmatism of 2.00 D, a channel width of 8.5 mm, and a channellength of 13.5 mm. The inventive lens also has an add power ofapproximately +2.00. However, in comparison, the inventive less has amaximum unwanted astigmatism of less than 1.00 D. Because the maximumunwanted astigmatism is below 1.00 D, the channel width is for allintents and purposes as wide as the lens itself. Lastly, the channellength is 14.5 mm. It should also be pointed out, that neither theVisionix VM-2500™ lens mapper nor the Rotlex Class Plus™ lens mapperwere able to detect unwanted astigmatism at the discontinuity in theinventive lens due to its small width.

TABLE II VARILUX ELLIPSE VARILUX PHYSIO INVENTION EMBODIMENT ATTRIBUTE(2.00 D ADD) (2.00 D ADD) (1D SPH LENS + 1D ADD PHYSIO) DISTANCE POWER0.12 D .O8 D −0.11 D NEAR TOTAL POWER 2.11 D 2.17 D 1.90 D TOTAL ADDPOWER 1.99 D 2.11 D 2.02 D CHANNEL LENGTH 13.5 MM 17.0 MM 14.5 MMCHANNEL WIDTH 8.5 MM 10.5 MM 23.5 MM MAX UNWANTED ASTIGMATISM 2.05 D1.68 D 0.90 D (BELOW THE MIDLINE) MAX UNWANTED ASTIGMATISM 0.98 D 0.95 D0.5 D (ABOVE THE MIDLINE)

The invention claimed is:
 1. A composite ophthalmic lens product, comprising: a first plastic layer comprising a first material having a first index of refraction; and a second plastic layer comprising a second material different from the first material and having a second index of refraction different than the first index of refraction, wherein, the first layer is in optical communication with at least a portion of the second layer, and the first layer and the second layer are configured to contribute to an optical power of a finished lens formed at least partially from the composite lens product, the first layer comprises a first thickness of approximately 1-1.5 mm, the second layer comprises a second thickness that is less than the first thickness, the lens product is configured to provide an ophthalmic optical correction to a user, wherein the first index of refraction is in a range of approximately 1.50 to 1.53 and the second index of refraction is in a range of approximately 1.60 to 1.67, and wherein the second layer includes a diffractive element.
 2. The lens product of claim 1, wherein the first index of refraction is approximately 1.53 and the second index of refraction is approximately 1.67.
 3. A composite ophthalmic lens product, comprising: a first plastic layer comprising a first material having a first index of refraction; a second plastic layer comprising a second material different from the first material and having a second index of refraction different than the first index of refraction; and a third plastic layer, wherein the second layer is disposed between the first layer and the third layer, wherein, the first layer is in optical communication with at least a portion of the second layer, and the first layer and the second layer are configured to contribute to an optical power of a finished lens formed at least partially from the composite lens product, the first layer comprises a first thickness of approximately 1-1.5 mm, the second layer comprises a second thickness that is less than the first thickness, the lens product is configured to provide an ophthalmic optical correction to a user, the first layer and the third layer are the same material, and the second layer is a different material than the first layer and the third layer, and wherein the second layer includes a diffractive element.
 4. The lens product of claim 3, wherein the lens is an at least partially finished lens blank.
 5. The lens product of claim 1, wherein: the second layer has a thickness of approximately 0.5 mm.
 6. The lens product of claim 1, wherein the lens is an at least partially finished lens blank.
 7. A composite ophthalmic lens product, comprising: a first plastic layer comprising a first material having a first index of refraction; and a second plastic layer comprising a second material different from the first material and having a second index of refraction different than the first index of refraction, wherein, the first layer is in optical communication with at least a portion of the second layer, and the first layer and the second layer are configured to contribute to an optical power of a finished lens formed at least partially from the composite lens product, the first layer comprises a first thickness of approximately 1-1.5 mm, the second layer comprises a second thickness that is less than the first thickness, the lens product is configured to provide an ophthalmic optical correction to a user, wherein the second layer is a preformed optical insert, and wherein the second layer includes a diffractive element.
 8. A composite ophthalmic lens product, comprising: a first plastic layer comprising a first material having a first index of refraction; and a second plastic layer comprising a second material different from the first material and having a second index of refraction different than the first index of refraction, wherein, the first layer is in optical communication with at least a portion of the second layer, and the first layer and the second layer are configured to contribute to an optical power of a finished lens formed at least partially from the composite lens product, the first layer comprises a first thickness of approximately 1-1.5 mm, the second layer comprises a second thickness that is less than the first thickness, the lens product is configured to provide an ophthalmic optical correction to a user, and wherein the second layer includes a diffractive element.
 9. The lens product of claim 8, wherein the first index of refraction is less than the second index of refraction.
 10. The lens product of claim 8, wherein the first layer includes a progressive optical power region.
 11. The lens product of claim 1, wherein the first layer includes a progressive optical power region.
 12. The lens product of claim 3, wherein the first index of refraction is less than the second index of refraction.
 13. The lens product of claim 7, wherein the first index of refraction is less than the second index of refraction. 